[BIO 130 LAB] 5 10-mm Frog Embryo.pdf

10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________...

10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ TABLE OF CONTENTS I. Whole Mount II. Level of Telencephalon, Diencephalon, & Mesencephalon IV. Level of Pronephros A. Prosencephalon B. Mesencephalon III. Level of Metencephalon & Myelencephalon V. Level of Tail C. Rhombencephalon I. WHOLE MOUNT To better understand and remember the structures of the frog embryo, it is important to review the 3 primary brain vesicles ○ All structures of the frog are derived from these 3 brain divisions which are further divided into the 5 secondary brain vesicles at the 10-mm embryo ○ Remembering which brain vesicle gives rise to specific structures will help in understanding its location and function within the embryo For example, since the rhombencephalon is responsible for respiratory and cardiovascular movements, the lungs and heart are located within this region PROSENCEPHALON ____________________________________________________________________________________________________________________________________________________________________________ Also known as the forebrain, it is the most rostral (toward the head) part of the embryo Differentiates into the telencephalon and diencephalon ○ Telencephalon Largest part of the brain that contains the cerebral lobes and basal ganglia. Gives rise to the cerebrum and limbic system Responsible for voluntary movement as well as olfaction, language, speech, learning, and memory ○ Diencephalon Gives rise to the epithalamus, hypothalamus, subthalamus, and the thalamus Responsible for coordination with the endocrine system in regulating the hormones, relaying information between sensory and motor neurons to the cerebral cortex, and regulates the circadian rhythms MESENCEPHALON ____________________________________________________________________________________________________________________________________________________________________________ Also known as the midbrain, it is the middle part of the embryo that is located at the most rostral part of the brainstem Does not differentiate, remains as the mesencephalon ○ Mesencephalon BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 1 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Gives rise to the dorsal and ventral midbrain which contains the superior and inferior colliculus Responsible for vision and auditory perception as well as pain sensory and the circadian rhythm RHOMBENCEPHALON ____________________________________________________________________________________________________________________________________________________________________________ Also known as the hindbrain, it is the most caudal part of the embryo Differentiates into the metencephalon and myelencephalon ○ Metencephalon Gives rise to the pons and cerebellum Responsible for auditory response, balance, and movement ○ Myelencephalon Gives rise to the medulla oblongata Responsible for respiration, gastric, and cardiovascular movements Figure 1: Primary and Secondary Brain Vesicles of The Frog Embryo BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 2 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figures 2 & 3: Whole Mount of the 10-mm Frog Embryo, Actual Slide (Left) and Cross-section Diagram (Right) BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 3 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ II. LEVEL OF TELENCEPHALON, DIENCEPHALON, & MESENCEPHALON The level of the telencephalon, diencephalon, and mesencephalon corresponds to key regions of the developing brain derived from the prosencephalon (forebrain) and the mesencephalon (midbrain). ○ The telencephalon appears as a pair of rounded, bulging masses at the most rostral (front) part of the brain. Key feature is the presence of its two cavities called the telocoele ○ The diencephalon lies between the telencephalon and the mesencephalon. It appears as a central region that is slightly narrower than the telencephalon but more elongated. Key feature is the presence of the circular epiphysis on top and the hanging anterior choroid plexus in the cavity. Optic vesicles are present on either side appearing as lateral outgrowths. ○ The mesencephalon or midbrain appears as a relatively compact structure posterior to the diencephalon. BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 4 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figure 4: Cross-Section of 10-mm Frog Embryo With Structures From The Level of The Telencephalon, Diencephalon, and Mesencephalon BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 5 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figure 5: Photomicrographs of 10-mm Frog Embryo With Structures From The Level of The Telencephalon, Diencephalon, and Mesencephalon II. LEVEL OF TELENCEPHALON, DIENCEPHALON, & MESENCEPHALON Structure Derivation/Predecessor Fate Description Function Prosencephalon Ectoderm Telencephalon & Forebrain; rounded, bulging mass at the Higher brain functions, sensory processing, Diencephalon anterior end of the neural tube with thin walls and regulation of visceraForms part of the and a central cavity brain ventricles, involved in CSF circulation activities Telencephalon Ectoderm Cerebral hemisphere, The rostral-most brain vesicle located cranial Involved in higher cognitive functions like hippocampus, & to the diencephalon thinking and memory​ olfactory lobes Pair of lateral organs for smell, association, Controls voluntary movements in the body and memory Telocoele Ectoderm 1st & 2nd brain Coelom or cavity of the telencephalon Forms part of the brain ventricles, involved ventricles (lateral); in CSF circulation 3rd brain ventricle BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 6 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ (median) Epidermis Ectoderm Skin and its Two-celled outer layer of the skin covering the Protective barrier appendages embryo Brain wall Ectoderm Ependymal layer Ectoderm Forms part of the Innermost layer of the neurocoele maintenance of homeostasis in the brain lining of the brain and formation of the blood–CSF barrier ventricles Mantle layer Ectoderm Gray matter of CNS Broad layer adjacent to the ependymal layer Marginal layer Ectoderm White matter of CNS Outermost fibrous layer of the brain wall Nasal cavity Ectoderm Nasal passageway Located in the cranial region of the embryo Olfactory Organ Ectoderm Olfactory epithelium Thickened patch of skin ectoderm ventrolateral to the telencephalon The medial lining of which becomes the olfactory epithelium Olfactory Pit Ectoderm Nasal cavity Cavity formed by invagination of the olfactory organ Melanophores Ectoderm Light brown stellate cells over the dorsolateral Melanin production and skin pigmentation surface of the brain Lateral to the nasal organs Cartilage Mesoderm Small masses of hyaline cartilages (prechordal or trabecular) Located beneath the telencephalic hemisphere Mesenchyme Mesoderm Dermis Stellate cells found between the spaces of the Fills in the spaces between the epidermis BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 7 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ epidermis and other organs and the internal organs Migratory in behavior Vomeronasal Organ Ectoderm Jacobson’s organ or lateral appendix; Detects olfactory stimuli from food in buccal dorsolateral evaginations of olfactory pits cavity Pharynx Endoderm Throat & esophagus Flat and broad gut tube Involved in the passage of food and air​ Large cavity in the level parallel to the level of Connects mouth with trachea and the optic cup and diencephalon esophagus Buccal cavity Ectoderm/endoderm Mouth & oral cavity Spacious chamber with flat epithelium where Involved in ingestion of food and initiation the mouth and the nasal passageways open; of digestion​ derived from stomodeum Receives food and air Lip Ectoderm Mouth opening Extension on the ventrolateral side of the mouth Teeth Ectoderm Dental structures Derived from stomodeum Mechanical breakdown of food Lateral thickenings within the buccal cavity Embryonic Teeth Ectoderm Precursor to adult Dorsal evagination in pharynx Assist in early development, later replaced teeth by adult teeth Diencephalon Ectoderm Optic vesicles, Second brain vesicle between telencephalon & Involved in sensory and motor signal relay, anterior choroid mesencephalon and autonomic function; regulates plexus, pineal gland, Derived from prosencephalon hormones infundibulum, Regulates involuntary processes thalamus, & hypothalamus Diocoele Ectoderm 3rd brain ventricle Cavity of the diencephalon Epiphysis Ectoderm Pineal gland Midline dorsal evagination of the roof of the Help control the circadian cycle of sleep and BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 8 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ diencephalon wakefulness Mesencephalon Ectoderm Corpora Midbrain; middle primary vesicle of embryonic Involved in vision, hearing, motor control, quadrigemina & brain and arousal​ cerebral peduncles Mesocoele Ectoderm Aqueduct of Sylvius Mesencoele; cavity of mesencephalon Connects the third and fourth ventricles, (cerebral aqueduct) Connects the diocoele to the rhombocoele allows CSF flow​ Anterior choroid plexus Mesoderm Vascularized non-nervous tissue that projects Produces CSF from the thin roof of the brain into the brain ventricles at the diencephalon (cranial choroid plexus) or myelencephalon (caudal choroid plexus) Infundibulum Ectoderm Posterior pituitary Funnel-like evagination of the floor of Forms the posterior pituitary gland, gland diencephalon regulates endocrine functions​ Anterior cardinal veins Mesoderm Internal jugular veins Paired veins that lie dorsolateral to the dorsal Drain blood from the head into the & cranial vena cava aorta common cardinal vein Return deoxygenated blood from the head to the heart Meninges Mesoderm Pia mater Three membranous coverings of the Protects the brain and spinal cord (innermost), vertebrate brain and spinal cord arachnoid, dura mater (outermost) Eyes Ectoderm Cornea, lens, retina, Complex sensory organs with multiple layers; Detects light and converts it into visual iris, lens vesicle, optic retinal development information nerve Cornea Ectoderm Cornea Outermost, transparent covering of the eye Refracts light BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 9 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Does not have its own blood supply but obtains nourishment from the aqueous humor Lens Ectoderm Lens Spherical body, arising as a vesicle; anterior to Focuses light the retina Partly enclosed by the optic cup Retina Ectoderm Retina Thick layer of the optic cup Captures light Pigmented retina Ectoderm Outer wall of the optic cup that contains Absorb excess light melanin pigment; dark layer of the retina Sensory retina Ectoderm Inner wall of the optic cup that forms the Produces optic fibers; contains rod cells and sensory layer of the retina glial cells to detect light Stratified due to the presence of different neuronal regions present Iris Ectoderm Iris Colored area of the eye that has the pupil in its Control the lens center Smooth muscle at the sides of the lens Lens vesicle Ectoderm Hollow spherical structure that arises from an invagination of the lens placode to the lens of the eye Lens epithelium Ectoderm Outer, thin layer of the lens vesicle. Lens fibers Ectoderm Without the inner thick area of the lens vesicle Optic nerve Ectoderm Cranial nerve II Sensory, paired nerve originating from the retina and migrates to the optic lobes (geniculate nucleus) via the optic stalk BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 10 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Internal carotid arteries Mesoderm Paired arteries that are an extension of the Provides oxygenated blood to the brain dorsal aorta in the head Oral sucker or adhesive Mesoderm Degenerates Horseshoe-shaped ectodermal gland located Produces mucous and functions in gland on the ventral side of the head of the embryo attachment Thyroid gland Endoderm Endocrine thyroid Begins as a median diverticulum of the Regulates metabolism and growth gland pharyngeal floor at the level of the hyoid Hormone production for metabolism arches and third pharyngeal arches regulation; secrete thyroxine to regulate Becomes differentiated into a dark, irregularly metabolism and promote metamorphosis shaped rudiment of the endocrine thyroid gland Hypobranchial cartilage Mesoderm Mass of long bar of cartilage below the floor of Supports the pharynx the foregut; granulated appearance Skeletal muscle Mesoderm Muscle Striated and pigmented appearance Movement of jaw III. LEVEL OF METENCEPHALON & MYELENCEPHALON Located at the mid-section of the frog embryo The metencephalon & myelencephalon are still in the form of the rhombencephalon Contains structures of the mid-section of organisms such as the auditory, cardiovascular, and respiratory organs CLUE! Look for the presence of the notochord or rhombocoele ○ First appearance of these structures also indicate the presence of the ear, blood vessels, heart, and certain parts of the frog’s respiratory system such as the operculum ○ Notochord is denoted by a circular hollow opening surrounded by somites ○ Rhombocoele is denoted by a triangular hollow opening BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 11 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figure 6: Cross-Section of 10-mm Frog Embryo With Structures From The Level of The Metencephalon & Myelencephalon BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 12 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figures 7: Photomicrographs of 10-mm Frog Embryo With Structures From The Level of The Telencephalon, Diencephalon, and Mesencephalon BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 13 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ III. LEVEL OF METENCEPHALON & MYELENCEPHALON Structure Derivation/Predecessor Fate Description Function Eventually develops into the pons, cerebellum, and medulla oblongata Hindbrain; most caudal region of the Cerebellum: motor coordination & learning, Metencephalon & embryonic brain Rhombencephalon Ectoderm balance or equilibrium, & posture Myelencephalon Located between the mesencephalon Pons: regulates signals & sleep-wake cycle (midbrain) and spinal cord Medulla oblongata: autonomic activities such as heartbeat & respiration Coelom or cavity of the rhombencephalon 4th ventricle (Caudal Rhombocoele Triangle shaped, white space below posterior Contributes into the 4th brain ventricle choroid plexus) choroid plexus The rostral most region of the Cerebellum: motor coordination & learning, Metencephalon Ectoderm Cerebellum & pons rhombencephalon. balance or equilibrium, & posture Between mesencephalon and myelencephalon Pons: regulates signals & sleep-wake cycle 4th ventricle (Caudal The cavity of the metencephalon that Metacoel choroid plexus) contributes to the fourth brain ventricle The caudal region of the rhombencephalon. Medulla oblongata & Medulla oblongata: autonomic activities Myelencephalon Ectoderm Lies between the metencephalon and spinal caudal choroid plexus such as heartbeat & respiration cord. 4th ventricle (Caudal The cavity of the myelencephalon that Myelocoele choroid plexus) contributes to the fourth brain ventricle Ear All; depends on part The auditory/otic vesicle Hearing & balance Endolymphatic duct Endoderm A thick-walled tube lying against the medulla Maintains fluid balance & pressure BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 14 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ which marks the course of the invagination of the auditory vesicle from the ectoderm The large chamber of the otic vesicle. Region of Utriculus & Utriculus Ectoderm the vestibular apparatus of the inner ear that Spatial orientation horizontally semicircular canals functions in balance Tthe outer ventral portion of the inner ear Sacculus Ectoderm Sacculus & cochlea from which the cochlea, the organ for hearing, Spatial orientation vertically arises The sacculations of the utriculus in the cranial, Semicircular canals Endoderm Maintains fluid balance & pressure horizontal, and caudal parts Auditory (acoustic) ganglion Parasympathetic functions Ganglia of the 8th Ectoderm Vestibular & spiral A dense mass located at the medial surface of Sound sensitivity & relays information to cranial nerve (neural crest) ganglia the auditory vesicle. nervous system Central bottom mass which has started Heart Mesoderm Pumps blood to and fro body functioning in the 4-mm embryo A double-walled sac derived from somatic Fixes heart in mediastinum and limits Pericardium Mesoderm mesoderm that envelope the heart motion Pericardial cavity Mesoderm A coelomic space that encloses the heart. Cushions heart against pressure Receives blood from primitive ventricle and Right ventricle & The anterior most chamber of the heart Bulbus cordis Mesoderm passes it to truncus arteriosus conus arteriosus connected to the ventral aorta Develops into right side of heart The chamber next to the bulbus cordis as it is Ventricle Mesoderm Pumps deoxygenated blood to lungs connected to the latter at the right side. BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 15 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ A large thin-walled chamber which is dorsally Atrium Mesoderm Left & right auricles Receives oxygenated blood to body located The caudal chamber of the embryonic heart Right atrium & Sinus venosus Mesoderm that receives blood from the major blood Heartbeat control inferior vena cava vessels and delivers it to the right atrium. Blood vessels Mesoderm Arteries and veins for blood transport Blood transport Paired vessels, Descending aorta One above each gill chamber and is continuous Carries oxygenated blood from the gills to Dorsal aorta Mesoderm (main artery) to caudal sections located between the gut and the rest of the body the chorda. Six paired arteries emanating from the aortic sac and traversing through the pharyngeal Develops into major vessels that transport Major arteries of Aortic arches Mesoderm arches to the paired dorsal aortae. blood to brain circulatory system Named according to the pharyngeal arch they Delivers blood to upper extremities traverse Major arteries of Paired vessels ventral to the pharynx and fuses Transports deoxygenated blood from heart Ventral aortae Mesoderm circulatory system to form the aortic sac. to gills Ganglia of 9th cranial Ectoderm Sensory, motor , Superior and petrossal ganglion supplies Relays gustatory information nerve (neural crest) gustatory ganglia sensory fibers to the glossopharyngeal nerve The sagittal skeletal rod beneath the hindbrain Nucleus pulposus of which is the primary structure in initiating the Primary skeletal support in embryonic Notochord Mesoderm intervertebral column formation of the central nervous system. stages discs This extends to the caudal region of the Replaced by spinal cord during maturation embryo Somites Mesoderm Varied Paired blocks of paraxial mesoderm located Give rise to repetitive structures BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 16 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ ventrolateral to the neural tube. First appear at the level of the caudal myelencephalon and then extend caudally to the tail Dorsal region of somite lying underneath the Dermatome Mesoderm Dermis, trunk, & tail skin ectoderm Region of somite that lies medioventral to the Myotome Mesoderm Skeletal muscles dermatome and gives rise to the skeletal musculature of the back, body wall and limbs Medioventral region of somite that gives rise to Sclerotome Mesoderm Spinal column & ribs the vertebral column and ribs Varied per arch; Blocks of pharyngeal wall that lie between the Give rise to bones (mandible, ear bones, includes oral jaw and pharyngeal pouches. Pharyngeal arches Mesoderm hyoid) and laryngeal cartilages (cricoid, parts of ear, tonsils, Externally they appear as bulges separated by thyroid, arytenoid) and thymus pharyngeal grooves Paired lateral evaginations of the wall of the Give rise to head and neck structures Pharyngeal pouches Endoderm Varied per pouch pharynx that extend to meet the overlying (Eustachian tube, tonsils, parathyroid ectoderm of the pharyngeal grooves glands) Slit or closing plate is a thin, double-walled partition made of skin ectoderm and Varied, including pharyngeal endoderm that is formed by the Give rise to head & neck structures Pharyngeal cleft Endoderm external auditory meeting of a groove and corresponding (external auditory meatus, hyoid & meatus & hyoid bone pharyngeal pouch. branchial arches) They rupture to leave a slit-like space, the pharyngeal cleft Glottis Endoderm Opening of the pharynx into the trachea or Opens windpipe for breathing & BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 17 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ larynx vocalization Ganglia of 10th cranial Ectoderm Superior & inferior Jugular ganglion provides sensory information Controls digestion, heart rate, and nerve (neural crest) ganglion to the vagus nerve immunity Trough in the ventral and caudal pharynx floor that elongates to form the trachea and larynx. Precursor to larynx & trachea Laryngo-tracheal groove Endoderm Larynx & trachea The lung buds form at the distal end of the Separates from esophagus elongated trachea Gives shape to organism and acts as shock Coelom Ectoderm or Endoderm Fluid-filled cavity of the embryo absorber The respiratory organ derived from the External or internal gill Endoderm Lungs pharyngeal arches 3 to 6. Gas exchange Lined with blood vessels of gills The growth of the skin from the second Operculum Ectoderm pharyngeal arch that covers the pharyngeal Protects the gills clefts in frog tadpoles. It internalizes the gill. IV. LEVEL OF PRONEPHROS The pronephros is typically found in the anterior region of the frog embryo, along the dorsal side, near the somites. It is positioned slightly behind the head region. In transverse sections, the pronephros appears as paired, segmented structures on either side of the embryo’s midline. ○ They will appear as a kidney-like structure with small rounded glomeruli and developing tubules BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 18 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ CLUE! Look for the presence of the digestive organs ○ The esophagus. liver, gallbladder, intestines, etc. all appear here ○ Intestines are characterized by serrated, disc-shaped tubes at the bottom part of the cross section Figures 8: Cross-Section of 10-mm Frog Embryo With Structures From The Level of Pronephros BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 19 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figures 9: Additional Cross-Section of 10-mm Frog Embryo With Structures From The Level of Pronephros BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 20 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figures 10: Photomicrographs of 10-mm Frog Embryo With Structures From The Level of The Pronephros IV. LEVEL OF PRONEPHROS Structure Derivation Fate Description Function Pronephros Mesoderm Cluster of small tubules or oval structures Embryonic excretory and osmoregulatory organ Degenerates lateral to the intestine Functions in tadpoles and degenerate after metamorphosis Degenerates Glomerulus Mesoderm Highly vascularized body lateral to dorsal aorta collects and filters waste materials in the blood and medial to pronephric tubules into the coelomic fluid BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 21 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Spinal cord Ectoderm Posterior continuation of the organizes and transmits nerve impulses from the myelencephalon until the tail PNS to the brain and mediates reflex movements Central canal - cavity of spinal cord containing cerebrospinal fluid Esophagus Endoderm Tube with folded endodermal Carries food to the stomach via peristalsis lining with wing-shaped cavity below the notochord Stomach Endoderm Large, thick-walled structure located at the Mechanical digestion of food ventrolateral region on the right side Secretes pepsin for chemical digestion of proteins Gastric gland rudiments - deep evaginations of the endodermal lining Hepatic portal vein in Hepatic portal Mesoderm A developing vein that forms part of the Transports nutrient-rich blood from the intestines to the adult frog vein embryonic circulatory system the liver for processing Degenerates Caudal cardinal Mesoderm Paired veins that run along the length of the Drain blood from the posterior part of the embryo and veins embryo’s body return it to the heart through the cardinal venous system Develops into parts Midgut Endoderm The middle portion of the developing gut, Forms most of the digestive tract and is responsible for of the small intestine situated between the foregut and hindgut nutrient absorption as the embryo develops Peripheral nervous Dorsal root Ectoderm; Neural Clusters of nerve cell bodies located outside Transmit sensory information from the body to the system ganglion or Spinal crest cells the spinal cord, along the dorsal roots of central nervous system ganglion spinal nerves Develops into parts Hindgut Endoderm The posterior section of the developing Forms the distal part of the digestive tract, where water of the urogenital digestive tube, located after the midgut absorption and waste formation take place system Intestines Endoderm; Oval structures with thick lining and elongated Primary site of chemical digestion and absorption of Midgut + hindgut lumen that is cut through several times due to food convolution BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 22 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Becomes the main Pleuroperitoneal Mesoderm; Large cavity where all the viscera are located Contains and lubricates most of major viscera except body cavity cavity Coelom the heart Lung buds Endoderm Thin-walled Paired oval structures on either side of Respiratory function in adults only alveolated lungs esophagus Liver Endoderm Mass of loosely organized cells adjacent to the processes compounds from absorbed food stomach on the right side detoxifies metabolites and produces bile Gallbladder Endoderm Small, round organ with a thin lining and a Stores, concentrates, and secretes bile cavity Pancreas Endoderm A mass of tissue between the liver and the Secretes pancreatic juice to the small intestine stomach after the gallbladder disappears posteriorly Myotomes Mesoderm Blocks of skeletal muscle on either side of Provide propulsion for swimming notochord V. LEVEL OF TAIL The tail sections are located beyond the point where the digestive tract ends as the tail is a structure that forms at the posterior extremity of the embryo. There is an absence of the other organs. BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 23 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ ○ Unlike more anterior sections, you will not see major internal organs (such as the heart or gut) in the tail region. Figure 11: Cross-Section of 10-mm Frog Embryo With Structures From The Level of Tail BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 24 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Figures 12: Photomicrographs of 10-mm Frog Embryo With Structures From The Level of The Tail BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 25 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ V. LEVEL OF TAIL Structure Derivation/Predecessor Fate Description Function Dorsal fin Ectodermal layer Regresses in adults Located above the spinal cord Increase surface area, aids in locomotion and provide stability Mesonephros Mesomere; Nephrotome Kidney Paired organ found beneath the dorsal aorta in Main excretory organ after the the caudal region degeneration of pronephros Produce urine in the frog Mesonephric tubules Mesomere Epididymis; Kidney Thick-walled Temporarily aids in kidney function and tubules Coiled tubules of the mesonephros with a later contribute to the development of the cup-shaped end male reproductive system Mesonephric duct Mesomere Excretory duct or Thick-walled Passage of gametes and other waste ureter Paired organ found beneath the dorsal aorta in products into the cloaca the caudal region Hindleg buds Ectoderm; Mesoderm; Hindlegs until Bulge on each side of the embryo For frog’s mobility on land when it becomes Somatopleure adulthood an adult Cloaca Ectoderm; derived from Cloaca Ventral invagination cranial to the ventral fin Exit passageway for liquid and solid wastes, proctodeum sperm, and eggs Caudal artery Mesoderm Caudal extension of the dorsal aorta Supplies oxygenated blood to the tail Blood vessel just below the notochord Caudal vein Mesoderm Blood vessel just below the caudal artery Drains blood from the tail into caudal cardinal veins Anus Ectoderm Proctodeum; ectoderm-lined depression near Final opening of the digestive tract for the hindgut waste excretion BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 26 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC 10-MM FROG EMBRYO BIO 130 LAB INTARMED 2030 | Dr. Vitor | LU2 SEM 1 | SY. 2024-2025 _____________________________________________ Ventral vein Ectoderm Located in the caudal end of the body Returns blood from the tail to the heart BIO 130 LAB LU 2 SEM 1 | IMED 2030 Page 27 of 27 DE LUNA, MD; RAPACON, I; VIDAL, IA; REYES, JCDC