HBS Anatomy Lectures PDF

Anatomical Terms By Dr. Rania Elsyade Assistant Professor of Anatomy and Embryology Faculty of Medicine, Helwan University  Objectives By the end of this lecture, students will be able to: 1. Define anatomy. 2. Elucidate how to s...

Anatomical Terms By Dr. Rania Elsyade Assistant Professor of Anatomy and Embryology Faculty of Medicine, Helwan University  Objectives By the end of this lecture, students will be able to: 1. Define anatomy. 2. Elucidate how to study anatomy. 3. Differentiate between regional and systemic anatomy. 4. Describe the anatomical position. 5. Identify the anatomical planes. 6. Identify the anatomical terms related to the position of structures. 7. Define the anatomical terms related to movement.  What is anatomy? Anatomy = Ana (Apart) + Tome (To Cut ) = To cut apart = Dissection Anatomy is the study of the human body structures and their relations to each other.  How to study anatomy? 1– Cadaveric Anatomy (Dissection). 2– Microscopic Anatomy (Histology). How to study anatomy? 3- Developmental Anatomy (Embryology). 4– Clinical Anatomy (Applied). How to study anatomy? 5 – Surface (Topographic or Living) Anatomy.  How to study anatomy? 6 – Radiographic Anatomy e.g. (PlainX-ray, US, CT & MRI). 7- Endoscopy.  How to study anatomy? 8 – Sectional Anatomy e.g. (CT & MRI). 9 –Comparative Anatomy.  How to study anatomy? 1 – Cadaveric Anatomy (Dissection). 2 – Microscopic Anatomy (Histology). 3 – Developmental Anatomy (Embryology). 4 – Clinical Anatomy (Applied). 5 – Surface (Topographic or Living) Anatomy. 6 – Radiographic Anatomy. 7 – Endoscopy. 8 – Sectional Anatomy. 9 –Comparative Anatomy. Differentiate between regional and systemic anatomy REGIONAL ANATOMY ✓Head & Neck. ✓Brain. ✓Trunk (Thorax –Abdomen –Pelvis & Perineum). ✓Extremities (or limbs) (Upper –Lower). Differentiate between regional and systemic anatomy SYSTEMIC ANATOMY ✓ Integumentary system ✓ Skeletal system ✓ Muscular system ✓ Nervous system ✓ Cardiovascular system ✓ Lymphatic system ✓ Endocrine system ✓ Digestive system ✓ Respiratory system ✓ Urogenital system  Describe the anatomical position. It is the standard reference position of the body used to describe the anatomical relations of the human body structures.  Describe the anatomical position. ✓ The body is standing upright. ✓ The face (eyes) looking forward. ✓ The upper limbs hanging by the side of the body and palms facing forward and fingers straight. ✓ The lower limbs are parallel with feet together and toes pointing forwards. list two criteria of the anatomical position.  Identify the anatomical planes. Sagittal planes: Coronal plane (frontal) Transverse plane (horizontal)  Identify the anatomical planes. ✓ Sagittal planes: These are vertical planes that divide the body into right and left parts. ✓ Midsagittal (Median) Plane: This passes in the midline of the body dividing it into equal right and left halves. ✓ Parasagittal (Paramedian) Planes: These are parallel to the midsagittal plane and divide the body into unequal right and left parts.  Identify the anatomical planes ✓ Coronal (frontal) plane: These are vertical planes perpendicular to the sagittal plane and divide the body into anterior and posterior parts. ✓ Transverse (or axial) planes: These are horizontal planes that divide the body into upper and lower parts Identify the anatomical terms related to the position of structures. ✓ Anterior/Ventral/ Rostral: near the front of the body. Dorsal planter ✓ Posterior/Dorsal: near the back of the body. Anterior Posterior ✓ Palmer: anterior surface of the hand. palmar ✓ planter: sole of the foot. Dorsal Identify the anatomical terms related to the position of structures. ✓ Superior/Cephali c/ Cranial: nearer to the head. ✓ Inferior/Caudal: nearer to the Superior Superior feet. Inferior Inferior Identify the anatomical terms related to the position of structures. ✓Median: at the midline of the body. ✓Medial: nearer to the midline of the body. ✓Lateral: nearer to the side of the body. Identify the anatomical terms related to the position of structures. ✓Proximal: near to the structure origin or root of the limb. ✓Distal: away from to the structure origin or root of the limb. ✓Intermediate: between 2 points. Identify the anatomical terms related to the position of structures. ✓Ipsilateral: same side of the body. ✓Contralateral: opposite side of the body. Identify the anatomical terms related to the position of structures. ✓Superficial: nearer to the surface of the body. ✓Deep: away from the surface of the body. Identify the anatomical terms related to the position of structures. ✓External: outside an organ or cavity. ✓Internal: inside an organ or cavity.  Define the anatomical terms related to the movements. ✓Flexion (bending): - Moving part is carried forwards - Movement on the transverse axis. ✓Extension (Straightening):- Moving part is carried backward – Movement on the transverse axis. ✓Planter Flexion and dorsi Flexion  Define the anatomical terms related to the movements. ✓Abduction: The moving part is carried away from the body/ reference line. – Movement on the anteroposterior axis. ✓Adduction: - The moving part is carried towards the body/reference line. -Movement on the anteroposterior axis.  Define the anatomical terms related to the movements. ✓ Medial Rotation: The moving part is rotated towards the midline. – Movement on the vertical axis. ✓ Lateral Rotation : The moving part is rotated away from the midline. – Movement on the vertical axis. Define the anatomical terms related to the movements.  Define the anatomical terms related to the movements. ✓ Circumduction: The moving part forms the base of a cone Test your self The anatomical term Abduction means………………… a.Near the root of the limb b.Outside an organ or cavity c.The moving part is carried away from the body. d.Opposite side of the body  References Gray’s Anatomy, 39th Edition Edited by Standring. Churchill Livingstone: Elsevier, 2004.  Dr. Eman El Sawaf Anatomy & Embryology Department Faculty Of Medicine, Helwan University Skeletal System  Objectives - By the end of this lecture student should be able to: Describe the anatomy of the skeletal system (4.1).  Contents - Definitions. - Functions of bones. - Classification of bones. - Long bones. Definitions  Skeleton (From Skeletos) = Hard It is formed by bones & cartilages. Osteology Study of bones. Functions Of Bones  Functions Of Bones Give shape and support for the body.  Functions Of Bones Protection for the vital organs.  Functions Of Bones Muscles attachment and movements.  Functions Of Bones Calcium & Phosphorus storage.  Functions Of Bones Formation of blood cells by the bone marrow. Remember Definitions Functions of bones Classification Of Bones  Classification Of Bones - Regional. - Developmental. - Structural. - Morphological.  Classification Of Bones Regional: (According to the region) - Axial: Skull, Sternum, Ribs &Vertebrae. - Appendicular: Bones of the upper & lower limbs.  Classification Of Bones Developmental: (According to the bone development). - Membranous. - Cartilaginous. - Membrano-cartilaginous (Mixed type).  Classification Of Bones Developmental: - Membranous: Bones which develop in a connective tissue membrane. Example: - Skull (the vault and the face bones). - Scapula.  Classification Of Bones Developmental: - Cartilaginous: Bones which develop in a model of hyaline cartilage. Example: - Bones forming the limbs.  Classification Of Bones Developmental: - Membrano-cartilaginous (Mixed type): Bones which develop partly in membrane and partly in cartilage. Example: - Mandible. - Clavicle.  Classification Of Bones Structural: (According to the structure) - Hard (Compact). - Spongy (Cancellous).  Classification Of Bones Structural: -Hard (Compact): It forms the cortical It is well developed and covering of all bones. thick in long bones.  Classification Of Bones Cancellous Structural: -Spongy (Cancellous): It forms the interior of Compact the ends of the long bone. The cancellous bone is Cancellous Compact always covered by outer shell of compact bone.  Classification Of Bones Compact Structural: -Spongy (Cancellous): It forms the interior of all other types of bones. Cancellous The cancellous bone is always covered by outer shell of compact bone. Compact Cancellous Remember Classification Regional Developmental Structural Morphological  Classification Of Bones Morphological: (According to the shape). Long (eg. Clavicle, humerus, femur ….) Short(eg. Carpals & Tarsals) Flat(eg. Scapula , Sternum, Ribs...) Irregular(eg. Vertebrae, hip…) Sessamoid(eg. Patella)  Classification Of Bones Morphological: Sesamoid bone - It is bony nodules which embedded in the tendons of some muscles & ligaments. - It protects the tendons and ligaments from compression and friction. e.g patella.  Classification Of Bones Morphological: Upper End Long bone The long bone has a shaft Shaft & two ends. Lower End  Classification Of Bones Upper End Morphological: (Epiphysis) Long bone Epiphyses - The 2 expanded articular ends of the long bone. Lower End (Epiphysis)  Classification Of Bones Morphological: Long bone Diaphysis -It forms the shaft. Shaft (Diaphysis) (central region of the long bone).  Classification Of Bones Morphological: Long bone Metaphysis Metaphysis - It is a part of the diaphysis adjacent to the epiphysis. Metaphysis  Classification Of Bones Morphological: Long bone Diaphysis -It is composed of a thick cortex compact bone. (1) 3 21 -The outer surface is covered by a membrane (the periosteum). (2) -Inside the shaft is the marrow (medullary) cavity filled with bone marrow. (3)  Classification Of Bones Morphological: Long bone - Functions of the periosteum:.Vascular supply and innervation of the bone..Bone growth in thickness. compact.Bone repair after fracture. bone Periosteum  Classification Of Bones Morphological: Long bone Diaphysis -The shaft has nutrient canal (foramen) for nutrient artery. (Arrow)  Classification Of Bones Epiphysis Morphological: Long bone Metaphysis Metaphysis & Epiphysis -They are composed of a spongy bone surrounded by a thin layer of compact bone.  Classification Of Bones Epiphysis Morphological: Epiphyseal Long bone plate Metaphysis Metaphysis & Epiphysis - The metaphysis is separated from the epiphysis by the epiphyseal plate of cartilage which is responsible for growth in length of long bone.  Classification Of Bones Plate Line Morphological: Long bone Metaphysis & Epiphysis - The epiphyseal plate of cartilage disappears after complete growth in length and it is replaced by the epiphyseal line. Remember Classification Morphological Sesamoid Long Epiphysis Diaphysis Metaphysis Marrow cavity Nutrient canal Periosteum Epiphseal plate & line  Blood Supply Of The Long Bones 4 1- Nutrient artery. 2- Periosteal arteries. 3 3- Metaphyseal arteries. 2 4- Epiphyseal arteries. 1 2  Nerve Supply Of The Long Bones 1- Sensory. 2- Vasomotor (Nerves accompany the blood vessels).  MCQ -Which one of the following is considered a regional type of bones? a. Membranous. b. Cartilaginous. c. Axial. d. Hard.  MCQ -Which one of the following is considered a regional type of bones? a. Membranous. b. Cartilaginous. c. Axial. d. Hard.  Reference BRS Gross Anatomy 6th Edition, Kyung Won Chung & Harold M.Chung. Images -Atlas of Human Anatomy -Netter – 2006 -TeachMe Anatomy -https://www.kenhub.com/en/library/anatomy/the-hip- adductors -https://commons.wikimedia.org/wiki/File:Scapula_- _anterior_view.png Thank You  ‫بسم الله‬ ‫الرحمن الرحيم‬ Prof.Mohamed Autifi Professor of Anatomy and Embryology Faculty of Medicine Al-Azhar University Basic Human Anatomy Prof. Mohamed A. Autifi Professor and Former Head of Anatomy & Embryology Department  Objectives Differentiation between differnet types of muscles in the body. Classification of muscles according to their fibers. Interaction of skeletal muscle.  Muscular System  The muscular system is composed of specialized cells called muscle fibers. Their predominant function is contractibility.  Nearly all movement in the body is the result of muscle contraction.  TYPES OF MUSCLES Skeletal Muscles 1. They are attached to bones and responsible for skeletal movements. 2. They are under conscious or voluntary control. 3. They are under control of somatic nervous system. 4. The basic unit is the muscle fiber with many nuclei. -These muscle fibers are striated (having transverse streaks) so they are called striated muscles. Prof. Mohamed Autifi  Muscular System Smooth Muscles 1. They are found in the walls of the hollow internal organs such as blood vessels, gastrointestinal tract, urinary bladder, and uterus. 2. They cannot be controlled consciously and thus acts involuntarily. 3. They are under control of the autonomic nervous system. 4. The non-striated (smooth) muscle cell is spindle-shaped and has one central nucleus. Prof. Mohamed Autifi  Muscular System Cardiac Muscle 1. They are found only in the heart wall. 2. They cannot be controlled consciously and thus acts involuntarily. 3. They are under control of the autonomic nervous system. 4. The cardiac muscle cell has one central nucleus, like smooth muscle, but it also is striated, like skeletal muscle. The cardiac muscle cell is rectangular in shape. The contraction of cardiac muscle is involuntary, strong, and rhythmical. Prof. Mohamed Autifi STRUCTURE OF SKELETAL MUSCLE A whole skeletal muscle is considered an organ of the muscular system. Each organ or muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and vascular tissue. Prof. Mohamed Autifi ARRANGEMENT OF MUSCLE FIBERS The muscles can be classified according to the arrangement of their fasciculi (fibers) into the following groups: a. Muscles with Parallel Fasciculi: These are muscles in which the fasciculi are parallel to the line of pull. These muscles may be: 1.Quadrilateral, e.g. thyrohyoid, 2.Strap-like, e.g. sternohyoid and sartorius. 3.Strap-like with tendinous intersections, e.g. rectus abdominis. 4.Fusiform, e.g. biceps brachii, digastric. The range of movement in such muscles is maximum. Prof. Mohamed Autifi ARRANGEMENT OF MUSCLE FIBERS b. Muscles with Oblique Fasciculi: These are muscles in which the fasciculi are oblique to the line of pull. These muscles may be: 1.Triangular, e.g. temporalis, adductor longus trapezius. 2.Pennate: a.Unipennate, e.g. flexor pollicis longus, extensor digitorum longus, peroneus tertius, palmar interossei. b.Bipennate, e.g. rectus femoris, dorsal interossei, peroneus longus, flexor hallucis longus. c.Multipennate, e.g. subscapularis, deltoid (acromial fibers]. d.Circumpennate, e.g. tibialis anterior. Prof. Mohamed Autifi ARRANGEMENT OF MUSCLE FIBERS c. Muscles with Spiral or Twisted or Convergent Fasciculi: Spiral or twisted fibers are found in trapezius, pectoralis major, latissimus dorsi, supinator, etc. In certain muscles the fasciculi are crossed and called cruciate muscles, e.g. sternocleidomastoid, masseter and adductor magnus. Prof. Mohamed Autifi Prof. Mohamed Autifi Interaction of skeletal muscles  Each movement at a joint is brought about by a coordinated activity of different groups of muscles. These muscle groups are classified and named according to their function. 1. Prime Mover  Prime mover (agonists) is a muscle or a group of muscles that directly start the desired movement. When the biceps flex the elbow, it acts as prime mover while the triceps acts as antagonist. 2. Antagonists  Antagonists (opponents) oppose the prime movers. They help the prime movers by active controlled relaxation, so that the desired movement is smooth and precise. They are responsible for returning a limb to its initial position. Prof. Mohamed Autifi Prime mover and antagonist Prof. Mohamed Autifi  Interaction of skeletal muscles 3. Fixators  Fixators are the group of muscles which stabilize the proximal joints of a limb, so that the desired movement at the distal joint may occur on a fixed base. Example: Muscles acting on shoulder joint fix it for better movement of fingers. 4. Synergists  When the prime movers cross more than one joint, the undesired actions at the proximal joints are prevented by certain muscles known as synergists. For example, during making a tight fist by long digital flexors , the wrist is kept fixed in extension by the synergists (extensors of wrist). Thus, the synergists are special fixators and partial antagonists to the prime movers. Two or more muscles causing one movement are synergist. Prof. Mohamed Autifi  Attachment of muscles  Most muscles are attached either directly or by means of their tendons or aponeuroses to bones, cartilages, ligaments, or fasciae, or to some combination of these. Other muscles are attached to organs, such as the eyeball, and still others are attached to skin.  When a muscle contracts and shortens, one of its attachments usually remains fixed and the other moves. The fixed attachment is called the origin, the movable one the insertion. In the limbs, the more distal parts are generally more mobile. Therefore the distal attachment is usually called the insertion. However, the anatomical insertion may remain fixed and the origin may move. Prof. Mohamed Autifi Blood supply of muscles  Muscles are supplied by adjacent vessels, but the pattern varies. Some muscles receive vessels that arise from a single stem, which enters either the belly or one of the ends, whereas others are supplied by a succession of anastomosing vessels. Nerve supply of muscles  Each muscle is supplied by one or more nerves, containing motor and sensory fibers that are usually derived from several spinal nerves.  Nerves usually enter the deep surface of a muscle. The point of entrance is known as the "motor point" of a muscle. Prof. Mohamed Autifi References  Standring S.(2021) Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 42nd ed. Philadelphia, PA: Elsevier, 2021.  Drake, R.L.; Vogl, A.W.; Mitchell, A.W.M. (2020): “Gray's anatomy for students”. 4th edition. Churchill Livingstone. Edinburgh, London, New York, Oxford, Philadelphia.  Moore, K. L.; Dalley, A. F. and Agur, A. M. R. (2017): “Clinically Orinted Anatomy”. 8th edition. Wolters Kluwer.  Ross and Wilson. (2014): “Anatomy &Physiology in health and illness”.12th edition, Churchill Livingstone. Edinburgh, London, New York Oxford, Philadelphia. Prof. Mohamed Autifi  I HOPE YOU HAVE ENJOYED THIS PRESENTATION Prof. Mohamed A. Autifi Prof. Mohamed A. Autifi  Articular System Hanan Mohammed Tarabeh Lecturer of Human Anatomy & Embryology Faculty of Medicine, Helwan University 2024  Objectives Define the articular system. Recognize the functions of the articular system. Identify the types of the joints. Differentiate between the types of the synovial joints.  Definition of the articular system Joints((articulations) of the body & the surrounding tissues.  Components of articular system Joints: are points of contact between 2 or more bones Ligaments: band of fibrous tissue that connects 2 bones. Tendons: connects the muscle to the bone. Cartilage. Bursae  Is the joint connects bones only?????  Functions of the articular System Movements. Weight bearing. Holding the skeleton together.  Classification of the joints According to the tissue between the articulating bones 3 types Fibrous Joints. Cartilaginous joints. Synovial joints.  I. Fibrous Joints thin layer of fibrous tissue between the 2 bones. Immobile (not moveable). A) Sutures: only found between the bones of the skull. There is limited movement until about 20 years of age, after which they become fixed and immobile. Most important in birth, allowing deformation of the skull as it passes through the birth canal.  B) Gomphoses teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth). The tooth is bound into its socket by the strong periodontal ligament.  C) Syndesmoses slightly movable joints. bones held together by an interosseous membrane. Exambles: middle radioulnar joint middle tibiofibular joint  II. Cartilagenous Joints slightly moveable. cartilage between the 2 bones. 1. Synchondroses (primary cartilaginous): the bones are connected by hyaline cartilage. These joints are immovable. example epiphyseal line (the joint between the diaphysis and epiphysis of a growing long bone).  2. Symphyses (secondary cartilaginous) bones are united by a layer of fibrocartilage. They are slightly movable. Examples pubic symphysis intervertebral discs (joints between vertebral bodies).  III. Synovial Joints 7 common components: 1. Articular capsule 2. Synovial membrane 3. Synovial fluid in a joint cavity. 4. Articular cartilage (hyaline cartilage covers the articular surfaces of the bones) 5. Capsular ligaments (localized thickening of the capsule) 6. Blood vessels 7. Sensory nerves  Types of the synovial joints 6 different types (shape of the articulating surfaces): 1. Plane joints: Articular surfaces are essentially flat Allow only gliding movements nonaxial joint E.g. intercarpal, intertarsal joints and vertebral articular processes  2. Hinge joints Cylindrical projections of one bone fits into a trough-shaped surface on another Motion is along a single transverse plane (like a mechanical hinge) Uniaxial joints permit flexion and extension only Examples: elbow and interphalangeal joints  3. Pivot Joints Rounded end of one bone protrudes into a ring composed of bone of another. uniaxial rotation of one bone around its own long axis. Examples: “No” motion of the head via joint between the 1st and the 2nd vertebrae superior radioulnar joint.  4. Condyloid or Ellipsoidal Joints Oval (convex) articular surface of one bone fits into a complementary depression (concave) in another. Biaxial joints permit all angular movements. Examples: radiocarpal (wrist) joints metacarpophalangeal (knuckle) joints Wrist joint  5. Saddle Joints Each articular surface has both a concave and a convex surface (concavoconex). Example:  carpometacarpal joint of the thumb.  6. Ball-and-Socket Joints A spherical or hemispherical head of one bone articulates with a cuplike socket of another. Multiaxial joints permit the most freely moving synovial joints. Examples: Shoulder joint. hip joint.  MCQ With regards to types of synovial joints, which of the following statements is true? o A hinge joint permits movement in two planes - flexion and extension. o The wrist joint is a ball and socket type joint. o In a plane joint, the articular surfaces slide over one another. o Synovial joints are functionally immobile.  References Gray's Anatomy for Students 3rd Edition. General Anatomy The Lymphatic System Prepared by Dr/ Manal Albadawi  Presented by Prof. Dr. Manal Albadawi Professor of Human Anatomy and Embryology A.Prof. Dr. Rania Elsyade Assistant Professor of Human Anatomy and Embryology (Faculty of Medicine- Helwan University)  Objectives By the end of this lecture students should understand the followings :  Defining anatomy of lymphatic system.  Describing site and functions of lymphatic system.  Identifying components of lymphatic system ( lymph vessels ,lymph nodes and lymphatic tissues).  Describing spleen site and structure.  Definition Drainage system, assist the venous system in return of excess interstitial fluids) Characters of lymph: clear but lymph from intestine has a milky appearance chyle rich in protein and lymphocytes passes through many filters called lymph node drains finally in venous system Site Site Function  Site & Function: -Maintaining the fluid balance -Immunity -Absorb the digested fat -Transport the large molecule (enzymes, hormones) Components: - Lymph fluid (Character – Formation – Circulation – Drainage) - Lymph capillaries (Character) - Lymph vessels (Character) - Lymph nodes (Site – Function) - Lymphatic tissues: Tonsils – Adenoid Spleen (Site – Structure) R. innominate v. - Lymph capillaries L. innominate v. - Lymph vessels Right lymphatic Thoracic duct - Lymph nodes duct - Lymph vessels ¼ Right ¾ Thoracic lymphatic duct duct Innominate veins Component of lymphatic system 1- lymph vessels: larger in diameter and more permeable than capillaries lymphatic capillaries join each other to form large vessels that contain valves interrupted by LN for filtration of foreign body materials like pus, bacteria and malignant cells. usually run along blood vessels toward the venous system finally all lymph vessels form two major ducts that end in corresponding innominate vein LT——————-> thoracic duct. RT————————> lymphatic duct 2-lymph node Collection of lymphoid tissue that lies along the course of lymph vessels and also in some strategic anatomical sites Axillary LN: in axilla Inguinal LN : in upper area of lower limb Cevical LN of the neck R. innominate v. L. innominate v. Thoracic duct Right lymphatic duct  Question ? What are the structures rich in lymphatics and those not rich in lymphatics? Structures without Structures rich in lymphatics lymphatics Brain, spinal cord Mucous membrane Bone marrow, spleen Serous membrane Cornea and cartilage Glands Epidermis Dermis Lymphatic tissues Spleen Site – Structure  Reference Gray’s Anatomy,39th Edition by Standring,hurchill Livingstone: Elsevier, 2004. Are We Together ??? Thank you Introduction to Anatomy Nervous system  Objectives Definition. Divisions of the Nervous Systems (CNS,PNS and ANS).  Central Nervous System: 1- Brain 2- Spinal cord  Peripheral nervous system  Autonomic nervous system Protection of the central nervous system  Definition  It is the system that is responsible for the control of all activities in the body.  It is formed of highly specialized nerve cell (neurone).  The neurone can receive the stimuli and send impulses to the effector (muscle or gland). Divisions of the nervous system Parts of The Nervous System The nervous system is divided into three main parts: 1- Central nervous system. 2- Peripheral nervous system. 3-Autonomic nervous system.  Divisions of the nervous system 1-Central nervous system - encased in bone  Brain within the skull  Spinal cord within the vertebral canal 2-Peripheral nervous system – voluntary control  Somatic nervous system cranial nerves  spinal nerves 3-Autonomic nervous system – no conscious control  Sympathetic nervous system – fight or flight response  Parasympathetic nervous system. 6  Central Nervous System (C.N.S.) The central nervous system consists of brain and spinal cord.  1) The Brain: Parts of the brain: 1. Cerebrum:  Formed of two cerebral hemispheres connected by the corpus callosum.  Each hemisphere has a lateral ventricle 2. Cerebellum:  Formed of two cerebellar hemisphere connected by the vermis. 3. Brain stem: Is formed of:  Midbrain: {above}.  Pons: {middle}.  Medulla oblongata :{ below}. cerebrum cerebellu m BS  Brain Cerebrum A. Cerebral hemisphere A B. Diencephalon 1: Thalamus 2: Hypothalamus 1 Cerebellum (C) 23 Brainstem 4 C 3: midbrain 4: pons 5 5: medulla - Forbrain:  Formed of two cerebral hemispheres.  Contain nuclei of the 1st & 2nd cranial nerves. - Midbrain:  Contains nuclei of the 3rd & 4th cranial nerves. - Hindbrain:  Formed of pons, medulla & cerebellum.  Pons: Contains nuclei of the 5th , 6th , 7th & 8th cranial nerves.  Medull: Contains nuclei of the 9th ,10th ,11th & 12th cranial nerves.  Medull: Contains centers of the heart, respiration, swallowing and vomitting.  Brain Cerebral hemisphere (cerebrum) and diencephalon Brain stem (midbrain, pons and medulla oblongata) Cerebellum 13  2) The Spinal cord: Begins: as the continuation of the medulla oblongata at the base of the skull. Ends: It ends at: - In the newborn: at the level of the third lumbar vertebra (L3). - In the adult: at the level of the lower border of (L1). Location: in the upper two-thirds of the vertebral canal. Length: 45 cm in the male and 42 cm in female Segments: 31 segments; which give rise of 31 pairs of spinal nerves. Enlargements: two enlargements: - Cervical enlargement: gives origin to the brachial plexus. - Lumbosacral enlargement: gives origin to the lumbosacral plexus. -Direct continuation of M.O. -Below foramen magnum. In upper 2/3 of vertebral canal. =45 cm in ♂ =42 cm in ♀  Spinal cord Anatomical position. segments Anatomical Cervical C planes.8 Thoracic T 12 Lumbar Anatomical terms.5[terminology] L Sacral S 5 Bone. Coccygeal 1 Anatomical position. Anatomical planes. Anatomical terms. [terminology] Bone.  2) The Spinal cord: Begins: as the continuation of the medulla oblongata at the base of the skull. Ends: It ends at: - In the newborn: at the level of the third lumbar vertebra (L3). - In the adult: at the level of the lower border of (L1). Location: in the upper two-thirds of the vertebral canal. Length: 45 cm in the male and 42 cm in female Segments: 31 segments; which give rise of 31 pairs of spinal nerves. Enlargements: two enlargements: - Cervical enlargement: gives origin to the brachial plexus. - Lumbosacral enlargement: gives origin to the lumbosacral plexus.  Protection of the CNS The brain and the spinal cord are protected by 3 barriers  The skull and the vertebral column  The meninges.  The cerebrospinal fluid  The Meninges Definition: are three membranes surround The brain and the spinal cord. The meninges consists of: 1. Dura mater (outer layer). 2. Arachnoid mater (middle layer). 3. Pia mater (inner layer).  The dura and arachnoid maters are separated by a space called subdural space.  The arachnoid and pia maters are separated by a space called subarachnoid space which contains cerebrospinal fluid.  Meninges - Three fibrous coats surround CNS. Meninges & meningeal spaces - Layers: 1- Dura matter: Outer, thickest and strongest layer. 2- Arachnoid matter: Middle layer. 3- Pia matter: Thinnest inner layer that lies in direct contact with brain and spinal cord. Meningeal spaces Epidural space : between dura and bone. Subdural space: between dura and arachnoid. Subarachnoid space :  Between arachnoid and pia.  The widest space.  Contains CSF.  The cerebrospinal fluid Definition: The fluid that fills the ventricles and subarachnoid space Volume: 130 ml Function: Reduces the brain weight. Drains the waste products. Protects the central nervous system. Regulates intracranial pressure.  Peripheral Nervous System Peripheral nervous system is formed of: a. cranial nerves b. spinal nerves c. ganglia.  Cranial Nerves  12 pairs connected to the brain Cranial Nerves  12 pairs connected to brain  Four Classifications of Cranial Nerves  Sensory nerves: carry somatic sensory information, including touch, pressure, vibration, temperature, and pain  Special sensory nerves: carry sensations such as smell, sight, hearing, balance  Motor nerves: axons of somatic motor neurons  Mixed nerves: mixture of motor and sensory fibers Name  1st 2nd 5th 7th 8th 9th 12th 11th 10th Cranial Nerves - Type and Function  Olfactory Nerves (I)  Special sensory (smell)  Optic Nerves (II)  Special sensory (vision)  Oculomotor Nerves (III)  Mixed (motor and parasympathetic) (eye movements)  The Trochlear Nerves (IV)  Motor (eye movements)  The Trigeminal Nerves (V)  Mixed (sensory and motor) to face Cranial Nerves - Type and Function  The Abducens Nerves (VI)  Motor (eye movements)  The Facial Nerves (VII)  Mixed (sensory, motor and parasympathetic) to face  The Vestibulocochlear Nerves (VIII) special sensory:  Vestibular branch:  balance and equilibrium  Cochlear branch:  Hearing Cranial Nerves - Type and Function  The Glossopharyngeal Nerves (IX)  Mixed (sensory, motor and parasympathetic) to head and neck  The Vagus Nerves (X)  Mixed (sensory, motor and parasympathetic)  Widely distributed in thorax and abdomen  The Accessory Nerves (XI)  Motor to muscles of neck and upper back  The Hypoglossal Nerves (XII)  Motor (tongue movements)  Spinal Nerves  31 pairs originate from the spinal cord  Spinalposition. Anatomical cord nerves Anatomical Cervical C 8planes. Thoracic T 12 Lumbar Anatomical terms. [terminology] L 5 Sacral S Bone. 5 Coccygeal 1  Autonomic nervous system It is the Part of nervous system concerned with innervation of involuntary structures as heart, smooth muscles & glands. It is distributed through central & peripheral nervous system. It is divided into 2 parts: a) Sympathetic system: thoracolumbar outflow  Prepare the body for an emergency.  It increases the heart rate, raises the blood pressure, inhibits peristalsis and closes the sphincters. b) Parasympathetic system: craniosacral outflow  Responsible for restoring energy.  It decreases the heart rate, increases the peristalsis an glandular activity and open sphincters.  Thank you Any questions????  Presented By: Professor Dr. Manal Al Badawi Dr. Eman El Sawaf Anatomy & Embryology Department Faculty Of Medicine, Helwan University Prepared By: Dr. Eman El Sawaf Introduction to Embryology  Objectives By the end of this lecture student should be able to: -Define the science of embryology. -Identify the different parts of genital system. -Identify the types of cell division.  Contents.Definition of embryology..Topics of embryology..Periods of prenatal development..Male and female reproductive systems..Types of cell division. Embryology  Definition of Embryology It is the science dealing with the development of the embryo from a single cell to 9 months baby.  Embryology Topics General embryology: -Gametogenesis. -Ovarian cycle & ovulation. -Fertilization. -Weeks of development. -Fetal membranes & placenta. Special embryology: Study the development of the different body systems and the congenital anomalies.  Periods of prenatal development Germinal period Embryonic period Fetal period  Periods of prenatal development Germinal First 2 From fertilization to the period weeks formation of the bilaminar embryonic disc.  Periods of prenatal development Embryonic From the -Formation of the period 3rd to 8th tissues and organs week (organogenesis). -The external features can be recognized.  Periods of prenatal development Fetal From the Maturation of tissues and period 9th week to organs and rapid growth birth of the body. Male & Female Reproductive Systems  Male & Female reproductive systems  Female reproductive system Parts: 1- Ovaries 2- Fallopian tubes (Uterine tubes) 3- Uterus 4- Vagina  Female reproductive system Parts of the uterus: 1- Fundus 2- Body 3- Cervix  Female reproductive system Parts of the Fallopian tube: 1- Intramural part (Interstitial) 2- Isthmus 3- Ampullary Part 4- Infundibulum 5- Fimbria  Male reproductive system Parts: 1- Testis 2- Epididymis 3- Vas deference 4- Seminal vesicle 5- Ejaculatory duct 6- Prostate  Male reproductive system Parts: 1- Testis 2- Epididymis 3- Vas deference 4- Seminal vesicle 5- Ejaculatory duct 6- Prostate  Male reproductive system Testes Seminiferous tubules Cell Divisions  Mitotic division One cell (46 chromosomes) Divides by mitosis 2 Daughter cells each contains the diploid number of chromosomes (46).  Meiotic division -The meiotic division occurs only in sex (germ) cells. - It generates male and female gametes (sperms and ovum cells).  Meiotic division One cell (46 chromosomes) Divides by meiosis I 2 daughter cells each contains the haploid number of chromosomes (23) Divide by meiosis II 4 daughter cells each contains the haploid number of chromosomes (23) -Definition of embryology -Topics of embryology -Periods of prenatal development -Reproductive system -Cell divisions  MCQ -Which one of the following belongs to the uterine tube? a. Fundus. b. Body. c. Cervix. d. Isthmus.  MCQ -Which one of the following belongs to the uterine tube? a. Fundus. b. Body. c. Cervix. d. Isthmus.  MCQ -Which one of the following is the correct time of the embryonic period? a. The first 2 weeks. b. The last 2 months. c. From the 3rd to 8th week. d. From the 9th week to birth.  MCQ -Which one of the following is the correct time of the embryonic period? a. The first 2 weeks. b. The last 2 months. c. From the 3rd to 8th week. d. From the 9th week to birth.  Reference -Langman’s Medical Embryology 13th Edition, T.W. Sadler. Images: - Langman’s Medical Embryology - https://www.pinterest.com/pin/204350901824989137/ - http://people.upei.ca/bate/html/notesontesticularfunction.html - https://www.shutterstock.com/image-vector/sperm-cell-human-body-anatomical-diagram-607006469 - https://study.com/academy/lesson/gametes-definition-formation-fusion.html - https://theconversation.com/study-confirms-flushing-blocked-fallopian-tubes-can-improve-fertility-and-reduce-need-for-ivf-77627 - https://www.britannica.com/science/human-reproductive-system - https://extendfertility.com/your-fertility-3/egg-count/ - http://www.dzireivf.com/ovulation-induction/# - https://www.pinterest.com/pin/693554411344697779/ - https://www.evolvingsciences.com/Fertilisation%20and%20implantation%20.html - www.nucleusinc.com - https://makeagif.com/gif/ovulation-the-menstrual-cycle-narrated-3d-animation-youtube-a2K1Dp - https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.jaypeedigital.com%2FeReader%2Fchapter%2F9789350904961%2Fch2 &psig=AOvVaw1hgoCOl_t7VfBlq0s- V1kt&ust=1728508924102000&source=images&cd=vfe&opi=89978449&ved=0CAMQjB1qFwoTCMDssNrb_4gDFQAAAAAdAAAAAB AR - https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.verywellmind.com%2Fstages-of-prenatal-development- 2795073&psig=AOvVaw2eI55bFgkuvvUmLixRShRL&ust=1728508543749000&source=images&cd=vfe&opi=89978449&ved=0CAMQjB 1qFwoTCNj9uKDa_4gDFQAAAAAdAAAAABA_ Thank You  Gametogenesis & ovarian cycle Hanan Mohammed Tarabeh Lecturer of Human Anatomy & Embryology Faculty of Medicine, Helwan University 2024  Objectives Define the process of the gametogenesis. Recognize the oogenesis. Recognize the spermatogenesis. Identify the spermiogenesis. Define the ovarian cycle. Differentiate between the phases of the ovarian cycle.  Gametogenesis Definition: Formation of gametes. Site: Gametes develop in the gonads (sex cells). In males, it is spermatogenesis (formation of sperm). In females, it is oogenesis (formation of ova). Mitosis Meiosis  Oogenesis Definition: Process of differentiation of oogonia to mature oocyte. Site: cortex of the ovaries and in the oviducts. Time: Starts before birth.  Oogenesis (process) PGC(primordial germ cells) Oogonia mitosis &surrounded by follicular cells from the sufface epithelium. Meiosis (1st meoitic division) primary oocyte  The total number of primary oocytes: At birth: from 600,000 to 800,000. During childhood: most oocytes become atretic. by the beginning of puberty: only approximately 40,000 Ovulation: fewer than 500 will be  At puperty: primordial follicles acquir cavity (antrum) antral stages mature vesicular (Graffian) follicles. Follicular cells granulosa cells cummulus oophorus : Granulosa cells surrounding the oocyte. Theca cells from surronding ovarian connective tissue. Zona pellucida : layer of glycoprotein on the surface of oocyte.  As follicles continue to grow, cells of the theca folliculi organize into: 1) The theca interna: an inner layer of secretory cells. 2) The theca externa: outer fibrous capsule.  MCQ When does the oogenesis start? 1. Before birth 2. After birth 3. At puberty 4. After puberty  MCQ What is the result of Oogonia mitosis? 1. Primary oocyte 2. Secondary oocyte 3. First polar body 4. Second polar body  Spermatogenesis Definition: Process by which spermatogonia differentiate into mature spermatozoa. Time: Begins at puberty. Site: Spermatozoa are formed in the wall of seminiferous tubules of the testes.  Stages of Spermatogenesis Many cells of different sizes and shapes: (a) Various cell stages in spermatogenesis (b) Sertoli (sustentacular) cells: supporting cells, which are derived from the surface epithelium of the testis in the same manner as follicular cells, Sertoli cells provide support and nutrition to germ cells.  PGCs spermatogonial stem cell type A spermatogonia, spermatid type B spermatogonia primary meiosis I Secondary spermatocytes spermatocytes  Spermiogenesis Definition: The process of transformation of a circular spermatid to a spermatozoon. Stages: 4 (1) formation of the acrosome, (covers half of the nuclear surface and contains enzymes to assist in penetration of the egg and its surrounding layers during fertilization). (2) condensation of the nucleus; (3) formation of neck, middle piece, and tail. (4) shedding of most of the cytoplasm as residual bodies that are phagocytized by Sertoli cells Duration: form a spermatogonium to a mature spermatozoon: approximately 74 days approximately 300 million sperm cells are produced daily.  Spermatozoon An actively motile, free swimming cell. Parts: a head, neck and a tail (flagellum). Head: ovoid, consists of nucleus. The anterior 2/3rd of nucleus is covered by acrosomal cap.  MCQ Which one of the following cells are the supporting cells derived from the surface epithelium of testis? 1. Spermatogonia 2. Spermatocytes 3. Sertoli cells 4. Leydig cells  MCQ When does the spermatogenesis start? 1. Before birth 2. After birth 3. At puberty 4. After puberty  The Ovarian Cycle Definition: the growth and maturation of an oocyte in preparation for fertilization and reproduction. Duration: 28 days from puberty until menopause, as long as the female is not pregnant. Phases: 1. follicular phase. 2. Ovulation 3. luteal phase. 1) Follicular phase: days 1 to 14 includes the growth and preparing of oocyte follicles for ovulation 2) Ovulation: on day 14 the release of a mature egg 3) Luteal phase: days 15 to 28 includes the development of corpus luteum that produces estrogen and progesterone  The Follicular Phase (Follicles ) 1. Primordial follicles 2. Primary follicles 3. secondary follicles Primordial follicles home to primary oocytes. 15-20 primordial follicles are stimulated by follicle stimulating hormone (FSH) developing into a primary follicle. During the follicular phase, one primary follicle develops into a secondary follicle, which is larger.  HYPOTHALAMUS GnRH ANTERIOR PITUITARY FSH LH OVARY Follicle (Theca interna&granulosa cells) Estrogens  Follicular Development OVULATION  estrogen LH Mature vesicular ( Grafian follicle) 25 mm diameter At midcycle, LH surge leading to: 1. Oocytes complete meiosis I & meiosis II 2. Progesterone production by follicular cells 3. Follicle rupture ( ovulation) Some of the cumulus oophorus cells then rearrange themselves around the zona pellucida to form the corona radiata  The Luteal Phase (Corpus Luteum) After ovulation, granulosa cells &theca interna vascularized by surrounding vessels. Under the influence of LH, these cells develop a yellowish pigment and change into lutein cells, which form the corpus luteum and secrete estrogens and progesterone  Fate of corus luteum Corpus Albicans If fertilization does not occur: the corpus luteum shrinks because of degeneration of lutean cells (luteolysis) and forms a mass of fibrotic scar tissue. Simultaneously, progesterone production decreases, precipitating menstrual bleeding.  If the oocyte is fertilized, degeneration of the corpus luteum is prevented by human chorionic gonadotropin, a hormone secreted by the developing embryo. The corpus luteum continues to grow and forms the corpus luteum of pregnancy (corpus luteum graviditatis). Removal of the corpus luteum of pregnancy before the fourth month usually leads to abortion.  MCQ Which one of the following hormones is the main cause of ovulation? FSH Prolactin LH Growth  Reference Langman’s Medical Embryology The first week of Development Fertilization By Dr. Rania Elsyade Assistant Professor of Anatomy and Embryology Faculty of Medicine, Helwan University  Objectives By the end of this lecture, students will be able to: 1. Elucidate the formation of corpus luteum and corpus albicans. 2. Define fertilization. 3. Mention the normal site of fertilization. 4. Describe the Capacitation and acrosome reaction. 5. Describe the phases of fertilization. 6. Identify the results of fertilization. Elucidate the formation of corpus luteum and corpus albicans corpus luteum If fertilization doesn’t occur corpus After albicans ovulation If fertilization corpus luteum occurs of pregnancy  Elucidate the formation of corpus luteum 1. After ovulation, granulosa cells remaining in the wall of the ruptured follicle, together with cells from the theca interna, are vascularized by surrounding vessels.  Elucidate the formation of corpus luteum 2. Under the influence of LH, these cells develop a yellowish pigment and change into lutein cells, which form the corpus luteum and secrete estrogens and progesterone.  Elucidate the formation of corpus albicans 3. If fertilization does not occur, ✓ the corpus luteum reaches maximum development approximately 9 days after ovulation. ✓ It can easily be recognized as a yellowish projection on the surface of the ovary. ✓ Subsequently, the corpus luteum shrinks because of the degeneration of lutein cells (luteolysis) and forms a mass of fibrotic scar tissue, the Corpus albicans.  Define fertilization It is the process by which male and female gametes fuse.  Mention the normal site of fertilization occurs in the widest part (ampullary) region of the uterine tube.  Capacitation and acrosome reaction Spermatozoa are not able to fertilize the oocyte immediately upon arrival in the female genital tract but must undergo capacitation and acrosome reaction to acquire this capability.  Capacitation Definition: It is a period of conditioning of the sperm and includes epithelial interactions between the sperm and the mucosal surface of the tube. Site: In the female reproductive tract mainly the uterine tube. Duration: approximately 7 hours. N.B. Speeding to the ampulla is not an advantage because capacitation has not yet occurred and such sperm are not capable of fertilizing the egg.  Capacitation Process: removal of a glycoprotein coat and seminal plasma proteins from the plasma membrane that overlies the spermatozoa. N.B. Only capacitated sperm can pass through the corona cells and undergo the acrosome reaction.  The acrosome reaction Time: after binding to the zona pellucida (zona proteins induce it). Process: The release of enzymes (including acrosin- and trypsin-like substances) is needed to penetrate the zona pellucida. Describe the phases of fertilization  Describe the phases of fertilization Phase 1: Penetration of the Corona Radiata. Phase 2: Penetration of the Zona Pellucida. Phase 3: Fusion of the Oocyte and Sperm Cell Membranes  Describe the phases of fertilization Phase 2: Penetration of the Zona Pellucida: The zona is a glycoprotein shell surrounding the egg that facilitates and maintains sperm binding and induces the acrosome reaction.  Describe the phases of fertilization Phase 3: Fusion of the Oocyte and Sperm Cell Membranes After adhesion, the plasma membranes of the sperm and egg fuse. The sperm head and tail enter the oocyte cytoplasm while the plasma membrane remains on the oocyte surface.  Describe the phases of fertilization When the sperm enter the oocyte cytoplasm the egg responds in three ways Cortical and Completion of Metabolic the second activation of the zona reaction meiotic division egg  Cortical and zonal reaction Definition: The release of lysosomal enzymes from cortical granules lining the plasma membrane of the oocyte when the head of the sperm comes in contact with the oocyte surface. N.B: Other spermatozoa have been found embedded in the zona pellucida, but only one seems to be able to penetrate the oocyte.  Describe the phases of fertilization Effects: (1) The oocyte membrane becomes impenetrable to other spermatozoa. (2) The zona pellucida alters its structure and composition to prevent sperm binding and penetration. These reactions prevent polyspermy (penetration of more than one spermatozoon into the oocyte). Describe the phases of fertilization  Describe the phases of fertilization 2. Resumption of the second meiotic division: ✓ The oocyte finishes its second meiotic division immediately after entry of the spermatozoon. ✓ One of the daughter cells, which receives hardly any cytoplasm, is known as the second polar body; the other daughter cell is the definitive oocyte. ✓ Its chromosomes (22 plus X) arrange themselves in a vesicular nucleus known as the female pronucleus.  Describe the phases of fertilization ✓ The spermatozoon moves forward until it lies close to the female pronucleus. ✓ Its nucleus becomes swollen and forms the male pronucleus. ✓ The tail detaches and degenerates.  Identify the results of fertilization 1. Restoration of the diploid number of chromosomes: half from the father and half from the mother. 2. Determinatíon of the sex of the new individual. An X- carrying sperm produces a female (XX) embryo, and a Y- carrying sperm produces a male (XY) embryo. Therefore, the chromosomal sex of the embryo is determined at fertilization. 3. Initiation of cleavage: Without fertilization, the oocyte usually degenerates 24 hours after ovulation. List three egg responses when the sperm enter the oocyte cytoplasm Enumerate three results of fertilization Which part of the uterine tube is the normal site of fertilization? a. Fimbrial part b. Ampullary part c. Isthmic part d. Intramural part Which of the following is the site of capacitation? a. Testis. b. Male genital ducts. c. Area surrounding the ovum. d. Uterine tubes. What is meant by Acrosome reaction? a. It is the meeting and union between male and female gametes. b. It is the release of lysosomal enzymes from cortical granules lining the plasma membrane of the oocyte. c. It is the conditioning of the sperm. d. It is a repeated mitotic division of the zygote. When does the completion of the second meiotic division of oocyte happen? a. During the uterine cycle. b. after entry of the spermatozoon to the oocyte. c. During implantation. d. During the uterine cycle.  References Langman’s Medical Embryology 13th Edition, T.W. Sadler. EMBRYOLOGY week one Prof. Doctor. Manal Albadawi DR, Hanan Tarabeh Objectives By the end of this lecture student should be able to describe the following events:  Cleavage (segmentation).  Blastocysts formation.  Start of implantation. Contact and fusion of the gametes  A direct contact between the spermatozoa and the zona pellucida of the secondary oocyte before actual fusion of the gametes.  The cells of corona radiata provide obstacle to the penetration of the sperms.  200 to 300 million sperms emitted at single ejaculation about 300 to 500 sperms reach the ovum, only 1 unites with oocyte & rest engaged in disintegration of corona radiata by secreting enzyme hyaluronidase.  Prior to penetration spermatozoa undergo process of capacitation and acrosome reaction.  COMPLETION OF SECOND MEIOTIC DIVISION OF FEMALE GAMETE It contains haploid number of chromosomes (22+ X). The bigger one is female pronucleus & smaller polar body pushed to peri-vitteline space. - Head and tail of sperm enter the cytoplasm. Head and neck of spermatozoon number of chromosome i.e. 22+X or 22+Y. RESTORATION OF DIPLOID NOS OF CHROMOSOMES IN THE ZYGOTE Both male & female pronuclie meet near centre of ovum, nuclear membrane disappear. This results in nuclear fusion with restoration of diploid number of chromosome 44+2X or 44+xy DETERMINATION OF THE CHROMOSOMAL SEX Out of the total population in that half of them contain x bearing chromosome and remaining half contain y bearing. If x bearing spermatozoon fertilizes an ovum the zygote contain 2x chromosome +44autosome & female child is formed & Zygote containing xy chromosome +44autosome male child is formed  Day 2 and 3: morulla/Cleavage  The original zygote divides about 30 hours after conception into two daughter cells called blastomeres.  Continued subdivisions with increasing numbers of blastomeres.  During cell division the dividing cells decrease in size. This type of cell division is called cleavage.  When zygote enter the uterus, it contains a solid ball of 12 to 16 blastomeres called the morula (mulberry). Day 4: Formation of the blastocyst  Fluid within the intercellular spaces of the morula gradually increases, and spaces on one side of the inner cell mass come together, forming a single cavity, the blastocele.  The outer layer organizes into the trophoblasts, which give rise to the placenta, and the inner layer of cells form the embryo.  The cavity of the blastocele fills with fluid, and the conceptus is now called the blastocyst. implantation–day 6 1. Apposition : most common occurs on the upper posterior uterine wall 2. Adhesion 3. Penetration and Invasion (Implantation occurs 6th or 7th day after fertilization). Implantation  MAJOR EVENTS OF FIRST WEEK NORMAL EVENTS POSSIBLE ABNORMAL EVENTS  Fertilization and formation of  Abnormal implantation the zygote (30hours).  Maternal infection or a  Cleavage of the zygote into 12 genetic defect to 16 blastomeres- the morula  Hydatidiform mole (day 2 and 3).  Abortion  Formation of the blastocyst  Ectopic implantation  ( day 5-8). Concerning the cleavage, which one of the following is correct?  The 2-cell stage is reached 20 hours after fertilization.  The 4-cell stage is reached 50 hours after fertilization  The 4-cell stage is called morula.  The 16-cell stage is called morula. Define the implantation and mention the beginning &site. Problem to solve  A woman has had several bouts of pelvic inflammatory disease and now wants to have children; however, she has been having difficulty becoming pregnant. What is likely to be the problem, and what would you suggest?  References Langman’s Medical Embryology 13th Edition, T.W. Sadler. Prof.Mohamed Autifi Professor of Anatomy and Embryology Faculty of Medicine Al-Azhar University Prof. Mohamed Autifi  And Lower Extremity Bones of the Pelvic Girdle Prof. Dr. Mohamed A. Autifi Former Head of Anatomy and Embryology Dept. Faculty of Medicine, Al-Azhar University Prof. Mohamed A. Autifi Revision of the first week Prof. Mohamed A. Autifi  CHANGES OCCURRING DURING FIRST WEEK 1. Fertilization 2. Segmentation (Cleavage) 3. Implantation Prof. Mohamed A. Autifi  Fertilization Is the union of spermatozoon with the mature ovum to form the zygote Normal site of fertilization: the lateral third of the uterine tube. Prof. Mohamed A. Autifi  Fertilization Phases of fertilization First phase The ovum is attacked by number of sperms. The sperms passes within the cells of corona radiata which are dispersed by the effect of enzymes derived from sperm as well as from the tubal mucosa. Prof. Mohamed A. Autifi  Fertilization Phases of fertilization Second phase As zona pellucida is attacked by spermatozoa: -One of them succeeds in penetration through the zona pellucida. -Penetration of spermatozoon through zona pellucida is helped by release of hyalurinidase enzyme secreted by acrosomal cap at the site of penetration. Prof. Mohamed A. Autifi  Fertilization Phases of fertilization Third phase During this phase fusion of the sperm cell membrane with that of the ovum occurs. The sperm head, neck pass into the ovum. Immediately, the zona pellucida and ovum cell membrane become impenetrable to other sperms. Prof. Mohamed A. Autifi  Fertilization Phases of fertilization Fourth phase The nucleus of the sperm swells to form male pronucleus. In the same time the nucleus of the mature ovum enlarges to form the female pronucleus. Prof. Mohamed A. Autifi  Fertilization Phases of fertilization Fifth phase The male pronucleus and female pronucleus fuse together to form a single nucleus called: segmentation nucleus. Prof. Mohamed A. Autifi Prof. Mohamed A. Autifi  Results of fertilization 1. Restoration of the full number of chromosomes (46). 2. Primary determination of the sex of embryo. ♣If the ovum is fertilized by sperm carrying Y chromosome the embryo will be a male. ♣If the ovum is fertilized by sperm carrying X chromosome the embryo will be a female. 3. Segmentation immediately follows fertilization. 4. Inheritance of characters of both parents. Prof. Mohamed A. Autifi  Segmentation (Cleavage) It is a series of cell divisions which occur in the zygote just after fertilization. Prof. Mohamed A. Autifi  Segmentation (Cleavage) Clevage divisions occur inside the zona pellucida, while morula is moving inside the uterine tube towards its uterine opening. Functions of zona pellucida 1. Limitation of the size of the zygote because zona pellucida is non-strechable and the number of cells is increased but the size of the whole cell mass is not increased. 2. Prevents adherence of the morula to the mucosa of the uterine tube. 3. Source of fertilizin substance which triggers acrosomal reaction that occurs between zona and acrosome of sperm. 4. Recognizes species of the sperms , i.e. human or not?. Prof. Mohamed A. Autifi  Segmentation (Cleavage) Blastocyst formation By end of third day after fertilization, -The morula reaches the uterine cavity. -The intercellular fluid in the morula starts to increase. - Fluid accumulation increases the pressure inside the morula, with an increase in the size of conceptus. - The fluid collects inside the morula forming a cavity, blastocele, and morula thus changes into a blastocyst. - This results into rupture of zona pellucida during 5th day, i.e. blastocyst hatching. Blastocyst remains free in the uterine cavity for 2-3 days Prof. Mohamed A. Autifi  Segmentation (Cleavage) Blastocyst formation - During 5th day, the blastocele cavity separates some cells to a side of the blastocyst, these cells are known as the embryoblasts or the inner cell mass. - The other cells around the cavity and the inner cell mass are flattened forming a peripheral layer of cells, known as the trophoblast. - The inner cell mass (formative cells) will develop later into the different embryonic tissues; while the trophoblast layer will form later the placenta and the fetal membranes. By the 6th day, blastocyst starts to embed itself in the wall of uterus. Prof. Mohamed A. Autifi Blastocyst Prof. Mohamed A. Autifi Fertilization, cleavage and implantation Prof. Mohamed A. Autifi Prof. Mohamed A. Autifi  Implantation It the process by which the blastocyst burrows into and embeds within the endometrium of the uterus. It starts by 6th day after fertilization. Implantation begins by adhesion of polar trophoblasts of the blastocyst to the uterine epithelium by secreting a digestive enzyme. During implantation, the entire trophoblastic layer undergoes rapid divisions. Thus, the wall of blastocyst is differentiated into: - an inner cellular layer, the cytotrophoblastic layer. - an outer layer, the syncytiotrophoblastic layer. Prof. Mohamed A. Autifi Prof. Mohamed A. Autifi  Implantation Normal site of implantation In the posterior wall of uterus near fundus. Abnormal sites of implantation Ectopic Pregnancy May be Uterine or Extrauterine Prof. Mohamed A. Autifi  Implantation Abnormal sites of implantation A. Uterine sites: Implantation in the lower uterine segment is called placenta previa. It occurs in 0.5% of pregnancies. It may be: A- Placenta previa centralis: Implantation site covers the internal os. B,C- Placenta previa marginalis: Implantation site reaches the margin of the internal os. D- Placenta previa lateralis: Implantation is in the lateral uterine wall away from internal os. Prof. Mohamed A. Autifi  Implantation Abnormal sites of implantation A. Extrauterine sites: 1- Tubal pregnancy: Implantation occurs in the wall of uterine tube. Tube usually ruptures in 2nd month of pregnancy. As a result, embryo is discharged into peritoneal cavity, usually dies. Serious hemorrhage occurs into the peritoneal cavity. 2- Interstitial pregnancy: The blastocyst burrows deeper and deeper into the uterine mucosa till the whole of it comes to lie within the thickness of the endometrium. 3- Ovarian pregnancy: Very rare, implantation occurs in the ovary. 4- Cervical pregnancy: Very rare, due to implantation occurs in the cervix of the uterus. Pregnancy is not completed. 5- Primary abdominal pregnancy: Very rare, implantation occurs into the peritoneum. Prof. Mohamed A. Autifi Prof. Mohamed A. Autifi  Decidua It is the endometrium of fundus and body of uterus after implantation. Decidua is differentiates into: a) Decidua capsularis: covers conceptus. b) Decidua basalis: between conceptus and uterine wall. c) Decidua parietalis: lines rest of uterine wall. The angle at which the three deciduae meet is known as the decidua reflexa. Prof. Mohamed A. Autifi  Decidua Fate of decidua With embryonic and amniotic growth, decidua capsularis is thinned and space between it and decidua parietalis is obliterated by their contact at beginning of 3rd month. By 5th month (22 W), The decidua capsularis is greatly thinned and disappears. The decidua parietalis atrophies by increasing pressure. The decidua basalis forms the maternal part of the placenta Prof. Mohamed A. Autifi  CHANGES OCCURRING DURING SECOND WEEK 1. Formation of bilaminar germ disc 2. Formation chorionic vesicle Prof. Mohamed Autifi  Objectives Describe the formation of bilaminar germ disc. Describe the formation of chorionic vesicle. Prof. Mohamed Autifi  Changes during second week Formation of bilaminar germ disc At day 8, cells of inner cell mass differentiates into 2 layers: a) Layer of small cuboidal cells facing blastocele, hypoblast (embryonic or primary endoderm); b) Remaining cells form layer of high columnar cells, subjacent to cytotrophoblasts of embryonic pole, epiblast (embryonic ectoderm). - Both layers form a flat circular plate, bilaminar embryonic germ disc. This embryonic plate will form the future embryo. Prof. Mohamed Autifi  Changes during second week Formation of bilaminar germ disc (day 8) A small cavity starts in inner cell mass, separates the disc from the trophoblast: amnion (amniotic vesicle). A layer of amniotic epithelium (amnioblasts) is formed from margins of disc & extends to line the cavity by day 9. Prof. Mohamed Autifi  Changes during second week Formation of bilaminar germ disc (day 8) The blastocoele becomes lined with a layer of flat cells, derived from hypoblast, extraembryonic mesoderm (exocelomic or Heuser’s membrane), completed by day 9. Blastocoele is now called primary yolk sac. Prof. Mohamed Autifi  Changes during second week Formation of bilaminar germ disc (day 9) Spaces appear in the syncytiotrophoblast, fuse to form large lacunae (lacunar stage), soon filled with mixture of maternal blood from eroded capillaries (sinusoids) & endometrial glandular secretions, Prof. Mohamed Autifi  Changes during second week Formation of bilaminar germ disc (day 10) blastocyst is completely embedded in the functional layer of endometrium. Prof. Mohamed Autifi  Changes during second week (day 11) New tissue: primary or extraembryonic mesoderm (EEM) is formed by delamination of cells from inner aspect of cytotrophoblast. It surrounds yolk sac and amniotic sac, separating them from trophoblast. Prof. Mohamed Autifi  Changes during second week (day 12) Clefts develop in the EEM. later the clefts fuse to form a single cavity, extraembryonic celom (EEC) or chorionic cavity. Prof. Mohamed Autifi  Changes during second week (day 12) EEC separates EEM into: Outer somatic layer lining the trophoblast. Inner splanchnic (visceral) layer covering yolk and amniotic sacs. Both layers are connected at one site that forms the body or connecting stalk. Yolk sac is now known as secondary yolk sac. The 2 layers of the trophoblast together with the somatic mesodermal layer are known as the chorion. While the whole conceptus is known as the chorionic vesicle which is full developed by the end of second week. Prof. Mohamed Autifi  Changes during second week Formation of chorionic vesicle It is formed of 2 main parts; embryonic area and fetal membranes. A) Embryonic area: This is a circular or slightly oval bilaminar disc. -It is formed of a dorsal single layer of columnar cells, ectoderm (epiblast) and a ventral single layer of flat cells, endoderm (hypoblast) ventrally. -They are separated by a basement membrane. -The embryonic disc separates the amnion dorsally and the yolk sac ventrally. NB. This embryonic plate will give rise to the embryo. Prof. Mohamed Autifi  Changes during second week Formation of chorionic vesicle B) Fetal membranes: These are structures which do not enter into the formation of embryo, but are essential for its normal development. It include: 1. Chorion: - It includes the structures which form the wall of chorionic vesicle. -It is formed of 3 layers from outside inwards are; syncitio-trophoblast, cytotrophoblast and outer layer of primary mesoderm (somatic mesoderm). Chorion will share in the formation of placenta. Prof. Mohamed Autifi  Changes during second week Formation of chorionic vesicle B) Fetal membranes: 2. Amnion: It is a small cavity filled with amniotic fluid and is dorsal to the embryonic disc. 3. Yolk sac: It is ventral to the embryonic plate. It is now known as secondary yolk sac. -Both amnion and yolk sac are surrounded by the inner layer of primary mesoderm (splanchnic mesoderm). 4. Connecting (body) stalk: It is a band of primary mesoderm that connects the 2 layers of the primary mesoderm, in other words connects the caudal end of embryonic disc to the chorion. It will give rise later to the umbilical cord. Prof. Mohamed Autifi  Changes during second week Appearance of chorionic villi Cells of the cytotrophoblast proliferate locally forming cellular columns into the syncytiotrophoblast, which surrounds the cellular columns. The columns with its syncytial covering form the primary villi Prof. Mohamed Autifi  References T.W. Sadler (2024). Langman’s Medical Embryology, 15th ed. Wolters Kluwer, Mexico. Keith L. Moore, T.V.N. Persaud and Mark G. Torchia (2013). The Developing Human Clinically Oriented Embryology, 9th ed. Saunders, Philadelphia. Prof. Mohamed Autifi Prof. Mohamed Autifi Prepared By: Dr. Eman El Sawaf Presented By: Ass.Prof.Dr. Rania Elsyade Dr. Eman El Sawaf Anatomy & Embryology Department Faculty Of Medicine, Helwan University General Embryology  Objectives By the end of this lecture student should be able to: Study the 2nd week of development (Bilaminar germ disc) (Day 11, 12 & 13)  Contents -Day 11&12 blastocyst. -Day 13 blastocyst. -Abnormal implantation. Day 11 & 12  Day 11 & 12 Blastocyst is completely embedded in the endometrial stroma. Day 11 & 12  Day 11 & 12 Syncytiotrophoblast at the embryonic pole are characterized by lacunar spaces. The maternal blood capillaries (sinusoids) (S) are dilated and congested.  Day 11 & 12 Cells of the syncytiotrophoblast Penetrate deeper into the endometial stroma and erode the endothelial lining of the maternal capillaries (sinusoids).  Day 11 & 12 The lacunae (L) are connected with the sinusoids (S) and maternal blood enters the lacunar system. The starting of the uteroplacental circulation. Day 11 & 12  Day 11 & 12 New cells appear between the cytotrophoblast (externally) and the exocoelomic membrane & the amnion (internally) (The extraembryonic mesoderm). Day 11 & 12 Day 11 & 12  Day 11 & 12 Large cavities develop in the extraembryonic mesoderm.  Day 11 & 12 The cavities become confluent and form a new space. The extraembryonic cavity or chorionic cavity.  Day 11 & 12 Extraembryonic somatic mesoderm The extraem- bryonic mesoderm lining the cytotrophoblast and amnion Cytotrophoblast Extraembryonic cavity Extraembryonic splanchnic mesoderm: (chorionic cavity) The extraembryonic mesoderm covering the yolk sac  Day 11 & 12 The extraembryonic cavity surrounds the primitive yolk sac and the amniotic cavity, except at the connecting stalk (It connects the germ disc with the trophoblast). Day 11 & 12 With development of blood vessels in the connecting stalk it becomes the umbilical cord. Umbilical cord Day 11 & 12 (Day 13) Day 13 The surface defect in the endometrium is healed.  Day 13 The hypoblast produces new cells which prolifrate.  Day 13 The hypoblast produces new cells which prolifrate.  Day 13 New cavity is formed within the exocoelomic cavity it is known as secondary yolk sac or definitive yolk sac. Extraembryonic cavity (chorionic cavity)  Day 13 Large part of the exocoelomic cavity is pinched off and the exocoelomic cyst (C) is formed. The chorionic cavity expands (enlarges). Day 13 The extraembryonic somatic mesoderm is known as chorionic plate  Abnormal implantation sites 1-Inside the uterus: at the cervix (Placenta previa) 2-Outside the uterus: (Ectopic pregnancy)  Third week Days 11&12 Days 13 Abnormal implantation  MCQ - Which one of the following cavities appears in the extraembryonic mesoderm? a. Amniotic cavity. b. Primitive yolk sac. c. Definitive yolk sac. d. Chorionic cavity.  MCQ - Which one of the following cavities appears in the extraembryonic mesoderm? a. Amniotic cavity. b. Primitive yolk sac. c. Definitive yolk sac. d. Chorionic cavity.  Reference -Langman’s Medical Embryology 13th Edition, T.W. Sadler. Images: - Langman’s Medical Embryology - https://www.pinterest.com/pin/204350901824989137/ - https://gfycat.com/anguishedcavernousbobcat Foto: Denis Gavrilin -Kvindelige reproduktive system. Vektor illustration -General Embryology - Detailed Animation On Second Week Of Development Thank You Prepared By: Dr. Eman El Sawaf Presented By: Dr. Eman El Sawaf Dr. Hanan Tarabeh Anatomy & Embryology Department Faculty Of Medicine, Helwan University General Embryology  Objectives By the end of this lecture student should be able to: Study the 3rd week of development (Trilaminar germ disc)  Contents Gastrulation: -Definition -Time -Mechanism Growth of the embryonic disc. Gastrulation  - Definition Gastrulation - Time Gastrulation is the process by which the three germ layers (ectoderm, mesoderm and endoderm) are formed in the embryo. It occurs during the third week of gestation. Bilaminar embryonic disc  - Definition Gastrulation - Time Gastrulation is the process by which the three germ layers (ectoderm, mesoderm and endoderm) are formed in the embryo. It occurs during the third week of gestation. Trilaminar embryonic disc  Gastrulation Trilaminar embryonic disc  Mechanism Gastrulation (Primitive streak) Gastrulation begins with formation of the primitive streak (arrow) on the surface of the epiblast (E).  Mechanism Gastrulation (Primitive node) The cephalic end of the primitive streak is called the primitive node.  Mechanism Gastrulation (Primitive node) The primitive node is an elevated area with a central depression, the primitive pit.  Mechanism Gastrulation Cephalic end Primitive Primitive node pit Primitive streak Caudal end  -Define the gastrulation. -What is the time of gastrulation? -What is the first step in the process of gastrulation?  Invagination Gastrulation Mechanism Invagination is an inward movement of the epiblast cells toward the primitive streak.  Invagination Gastrulation Mechanism Invagination is an inward movement of the epiblast cells toward the primitive streak.  Invagination Gastrulation Mechanism Some of the cells of the epiblast migrate toward the primitive streak.  Invagination Gastrulation Mechanism When they arrive in the region of the streak, they detach from the epiblast and slip below it.  Invagination Gastrulation Mechanism Some of the cells of the epiblast migrate toward the primitive streak.  Invagination Gastrulation Mechanism When they arrive in the region of the streak, they detach from the epiblast and slip below it.  3 Germ layers Gastrulation Mechanism Once the cells have invaginated: Some cells displace the hypoblast and form the embryonic endoderm  3 Germ layers Gastrulation Mechanism Once the cells have invaginated: The cells which lie between the epiblast and the newly formed endoderm will form the mesoderm  3 Germ layers Gastrulation Mechanism Once the cells have invaginated: The remaining cells in the epiblast will form the ectoderm  3 Germ layers Gastrulation Mechanism  Gastrulation -The epiblast cells through the process of gastrulation is the source of all of the 3 germ layers. -The cells in these layers will form the tissues and organs in the embryo. Gastrulation -The beginning of the third week of develop- ment, when gastrulation is initiated, is a highly sensitive stage for teratogens.  End Gastrulation Invagination and cell migration continues until the end of the fourth week when the primitive streak rapidly shrinks and disappears.  -Define invagination. -What is the time of the end of invagination? Gastrulation Oropharyngeal (buccopharyngeal) membrane Cloacal membrane Gastrulation  Gastrulation Oropharyngeal (buccopharyngeal) membrane -It is formed at the cranial end of the embryonic disc. -It is formed of ectoderm and endoderm cells with no intervening mesoderm. -It is the future opening of the oral cavity.  Gastrulation -It is formed at the caudal end of the embryonic disc. -It is formed of ectoderm and endoderm cells with no intervening mesoderm. -It is the future opening of the anal canal. Cloacal membrane Growth Of The Embryonic Disc Growth of the embryonic disc  Growth of the embryonic disc The embryonic disc initially is flat and rounded.  Growth of the embryonic disc The embryonic disc gradually becomes elongated with a broad cephalic and a narrow caudal ends.  Growth of the embryonic disc The embryo develops cephalocaudally.  Third week - Gastrulation - Invagination - Ectodem – Mesoderm - Endoderm - Buccopharyngeal membrane - Cloacal membrane -Growth of the embryonic disc  MCQ - What is the process by which the three germ layers are formed? a. Implantation. b. Fertilization. c. Segmentation. d. Gastrulation.  MCQ - What is the process by which the three germ layers are formed? a. Implantation. b. Fertilization. c. Segmentation. d. Gastrulation.  MCQ - Concerning the cloacal membrane, which one of the following statements is true? a. It is formed of ectoderm only. b. It is formed of endoderm only. c. It is formed at the cranial end of the embryonic disc. d. It is formed at the caudal end of the embryonic disc.  MCQ - Concerning the cloacal membrane, which one of the following statements is true? a. It is formed of ectoderm only. b. It is formed of endoderm only. c. It is formed at the cranial end of the embryonic disc. d. It is formed at the caudal end of the embryonic disc.  Reference -Langman’s Medical Embryology 13th Edition, T.W. Sadler. - Langman’s Medical Embryology - https://www.pinterest.com/pin/204350901824989137/ -https://gfycat.com/gifs/search/gastrulation Foto: Denis Gavrilin -Kvindelige reproduktive system. Vektor illustration -General Embryology - Detailed Animation On gastrulation -https://www.studyblue.com/notes/note/n/53-animal development/deck/10751565 -http://embriologiapalabras.blogspot.com/p/segunda- semana-de-desarrollo.html - MONITORING STEM CELL RESEARCH Thank You  Presented By: Professor Dr. Manal Al Badawi Dr. Eman El Sawaf Anatomy & Embryology Department Faculty Of Medicine, Helwan University Prepared By: Dr. Eman El Sawaf General Embryology  Objectives By the end of this lecture student should be able to: Study the 3rd week of development (trilaminar disc)  Contents -Formation of the prechordal plate. -Formation of the notochord. -Formation of the neuroenteric canal. -Formation of the allantois.  Formation Of Prechordal Plate (mesoderm)  Formation of the prechordal plate Primitive node Some of the first cells that migrate through the primitive node form a thickened plate, it is called the prechordal plate.  Formation of the prechordal plate Some of the first cells that migrate through the primitive node form a thickened plate, it is called the prechordal plate. Prechordal plate  Formation of the prechordal plate The prechordal plate is important for induction of the forebrain. Prechordal plate Formation Of Notochord  Formation of the notochord - Some of the cells that invaginate the primitive node are called Prenotochordal cells. -They move Prenotochordal cells cranially in the midline until they reach the prechordal plate.  Formation of the notochord - Some of the cells that invaginate the primitive node are called Prenotochordal cells. -They move cranially in the midline until they reach the prechordal plate.  Formation of the notochord - Some of the cells that invaginate the primitive node are called Prenotochordal cells. -They move cranially in the midline until they reach the prechordal plate. Prechordal plate  Formation of the notochord Prenotochordal cells form a solid cord of cells, it is called the definitive notochord. Definitive notochord  Formation of the notochord Primitive Pit The notochord extends cranially to the prechordal plate and caudally to the primitive pit. Prechordal plate Definitive notochord  Cross section Formation of the notochord Notochord (Arrow) Ectoderm Mesoderm Endoderm  Formation of the notochord The notochord is a signaling center for inducing the axial skeleton.  Formation Of Neuroentric Canal  Formation of the neuroenteric canal Primitive pit (neuroenteric canal) -At the primitive pit an indentation is formed in the epiblast. -It forms a temporary canal that connects the amniotic cavity and the yolk sac (neurenteric canal).  Formation of the neuroenteric canal -At the primitive pit an indentation is formed in the epiblast -It forms a temporary canal that connects the amniotic cavity and the yolk sac (neurenteric canal). Formation Of Allantois Allentoentric diverticulum (Allantois) Connecting stalk  Allentoentric diverticulum (Allantois) Connecting stalk -By the 16th day the wall of the yolk sac forms a small diverticulum that extends into the connecting stalk. -It is called allantoenteric diverticulum Allantois (allantois).  Allentoentric diverticulum (Allantois) Connecting stalk -In lower vertebrates: The allantois serves as a reservoir for urine. -In humans:.It remains rudimentary..Part of the allantois remains in the connecting stalk and part is involved Allantois in the development of the urinary bladder. -Prechordal plate -Notochord -Neuroenteric canal -Allantois  MCQ - From which one of the following the allantois arises? a. The amniotic cavity. b. The yolk sac. c. The chorion. d. The connecting stalk.  MCQ - From which one of the following the allantois arises? a. The amniotic cavity. b. The yolk sac. c. The chorion. d. The connecting stalk.  Reference -Langman’s Medical Embryology 13th Edition, T.W. Sadler. Images: -Langman’s Medical Embryology -https://www.pinterest.com/pin/204350901824989137/ -http://staff.um.edu.mt/acus1/PlacentaTwins.htm -https://www.seeker.com/human-animal-embryo-research-could-get-us- funding-1960173276.html -https://fortune.com/2018/01/11/frozen-embryos-ivf-pcos/ -https://www.youtube.com/watch?v=sUuX-4fEF3A Thank You  Presented By: Professor Dr. Manal Al Badawi Dr. Eman El Sawaf Anatomy & Embryology Department Faculty Of Medicine, Helwan University Prepared By: Dr. Eman El Sawaf General Embryology  Objectives By the end of this lecture student should be able to: Study the embryonic period (3rd to 8th week) (Ectodermal layer)  Contents - Development of the ectodermal layer:.Neurulation..Neural crest cells..Derivatives of the neural crest..Derivatives of the ectoderm. Neurulation  Neurulation Ectoderm Mesoderm Endoderm  Neurulation The appearance of the prechordal mesoderm and the notochord induces the overlying ectoderm to thicken and form the neural plate (neuroectoderm). The initial stage in the process of neurulation.  Neurulation The appearance of the prechordal mesoderm and the notochord induces the overlying ectoderm to thicken and form the neural plate (neuroectoderm). The initial stage in the process of neurulation.  Neurulation Primitive node & pit Precordal mesoderm Notochord  Neurulation Neural plate  Neurulation Neurulation is the process by which the neural plate (1) forms the neural tube (2).  Neurulation The neural plate lengthens.  Neurulation The edges of the neural plate elevate to form the 2 neural folds and the mid region is depressed and forms the neural groove.  Neurulation -The 2 neural folds fuse gradually in the midline. -Fusion begins in the cervical region and proceeds cranially and caudally.  Neurulation The neural tube is formed.  Neurulation The cephalic and caudal ends of the neural tube are still opened and form. Cranial Caudal (anterior) (posterior) neuropore neuropore  Cranial neuropore Caudal neuropore  Neurulation Closure of Cranial Caudal (anterior) (posterior) neuropore neuropore Occurs at Occurs at day 25 day 28  Neurulation The neurulation is completed and the central nervous system is formed. The broad cephalic part of the neural tube forms the brain vesicles. The narrow caudal part forms the spinal cord.  Cross section Neurulation Neural plate  Neurulation Cross section Neural groove Neural fold Neural fold  Neurulation Cross section Neural groove Neural fold Neural fold Neurulation Cross section Neural tube  Cross section Neurulation  Neural tube defects (NTDs) NTDs occur due to failure in the closure of the neural tube.  Neural tube defects (NTDs) If the closure fails in the cranial part of the neural tube, most of the brain fails to form. Anencephaly  Neural tube defects (NTDs) If closure fails any where from the cervical region caudally. Spina bifida  Neural tube defects (NTDs) The folic acid administration reduces the NTDs.  Remember Neural plate Neurulation Neural folds Neural groove Neural tube Neuropores Neural tube defects Neural crest cells  Neural crest cells Cells at the margins of the neuroectoderm (neural plate) which separate and enter the underlying mesoderm.  Neural crest cells -Neural crest cells contribute to many organs and tissues. -They are called the fourth germ layer.  Neural crest derivatives -Dermis in Connective tissue face and neck and bones of the -Melanocytes face and skull Odontoblasts C cells of the thyroid gland  Neural crest derivatives Meninges Smooth muscle in the blood vessels of the face and forebrain  Neural crest derivatives Conotruncal septum in the heart Adrenal medulla Derivatives of the ectoderm  Derivatives of the ectoderm Sensory epithelium Central of the ear, nervous nose, and system eye Peripheral nervous