Embryogenesis and Early Development

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Questions and Answers

What is the primary function of the notochord during embryonic development?

To establish the body's left-right axis

To signal the development of surrounding tissues (correct)

To form the facial bones

To provide nourishment to the embryo

Which of the following is NOT a structure that neural crest cells give rise to?

Muscles of the trunk (correct)

Vertebrae of the neck

Facial bones

Peripheral nerves

What does the tropoblast contribute to in early embryonic development?

Formation of the yolk sac

Development of the amniotic cavity

Formation of the placenta (correct)

Establishment of the endometrial lining

The region known as the stomodeum in an embryo ultimately develops into which structure?

Mouth Signup and view all the answers

Which structure is responsible for the segmentation that contributes to the formation of muscles and bones in the neck?

Occipital somites Signup and view all the answers

What is the primary outcome of the process known as gastrulation?

Formation of three germ layers Signup and view all the answers

Which structure is the earliest extraembryonic structure that provides nourishment and involves blood cell formation?

Yolk sac Signup and view all the answers

During which stage does the neural plate fold to form the neural tube?

Neurulation Signup and view all the answers

Which of the following structures is created by the inner cell mass of the blastocyst?

Embryo Signup and view all the answers

Which germ layer is responsible for developing into the skin and nervous system?

Ectoderm Signup and view all the answers

The zona pellucida is vital for which of the following processes during early development?

Protecting the egg prior to fertilization Signup and view all the answers

What structure ultimately develops from the embryoblast?

Embryo Signup and view all the answers

What does the morula stage consist of?

A solid ball of 16 cells Signup and view all the answers

Which layer of the embryonic disc gives rise to the ectoderm and mesoderm?

Epiblast Signup and view all the answers

What is the function of the amniotic cavity during embryonic development?

Protects the embryo from mechanical shock Signup and view all the answers

What is the role of gametes in reproduction?

To combine and form a zygote Signup and view all the answers

What condition is characterized by the presence of a cleft in the upper or lower lip?

Cheiloschisis Signup and view all the answers

Which term describes a condition characterized by an abnormally small jaw?

Micrognathia Signup and view all the answers

What developmental structure, formed during early embryonic development, gives rise to structures in the head and neck?

Pharyngeal Arches Signup and view all the answers

What is the term for the condition where the facial features are absent?

Aprosopus Signup and view all the answers

Which condition refers to an abnormally enlarged head due to brain enlargement?

Macrocephaly Signup and view all the answers

What is the term for the premature closure of skull sutures impacting head shape?

Craniosynostosis Signup and view all the answers

Which term describes an abnormally large mouth resulting from incomplete fusion of facial processes?

Macrostomia Signup and view all the answers

Which condition involves the complete closure of the mouth?

Astomia Signup and view all the answers

Study Notes

Embryogenesis

Process by which a fertilized egg develops into a fully formed organism
Involves fertilization, cleavage, gastrulation, and organogenesis

Gastrulation

Embryo forms three primary germ layers: ectoderm, mesoderm, and endoderm
These layers develop into body tissues and organs

Neurulation

Neural plate folds to form the neural tube
Neural tube develops into the brain and spinal cord

Amniotic Cavity

Fluid-filled space surrounding the developing embryo
Provides protection and support

Blastula

Hollow ball of cells formed during early embryonic development
Follow the morula stage

Cleavage

Series of rapid cell divisions after fertilization
Results in a cluster of cells known as the blastocyst

Ectoderm

Outermost germ layer
Forms skin, nervous system, and sensory organs

Embryoblast

Inner cell mass of the blastocyst
Develops into the embryo

Embryonic Disc

Flat, bilayered structure from the embryoblast
Gives rise to ectoderm, mesoderm, and endoderm

Endoderm

Innermost germ layer
Forms the digestive system, lungs, other internal organs

Epiblast

Upper layer of the embryonic disc
Forms ectoderm and mesoderm

Fertilization

Sperm cell and egg cell combine to form a zygote
Initiates embryonic development

Gametes

Reproductive cells (sperm and egg)

Hypoblast

Lower layer of cells in the early embryo
Contributes to formation of extraembryonic tissues

Intermediate Mesoderm

Region of mesoderm
Gives rise to structures like kidneys and reproductive system

Lateral Plate Mesoderm

Part of the mesoderm
Forms heart, blood vessels, and parts of limbs

Mesoderm

Middle germ layer
Develops into muscles, bones, circulatory system

Morula

Ball of about 16 cells formed after the zygote divides
Enters the uterus 3 days after fertilization

Neural Crest Cells

Migrate from the developing neural tube to form peripheral nerves and facial bones

Notochord

Rod-like structure forming the basis for the vertebral column
Signals the development of surrounding tissues

Occipital Somites

Segmented blocks of mesoderm near the head
Contribute to muscle and vertebrae development (neck)

Paraxial Mesoderm

Mesodermal layer alongside the neural tube
Forms somites (muscles, bones, skin)

Primitive Node

Cluster of cells at anterior end of primitive streak
Involved in notochord formation and body axis patterning

Primitive Streak

Linear structure in early development
Establishes body's left-right and anterior-posterior axes

Trophoblast

Outer layer of cells in the blastocyst
Implants into uterine wall; forms part of placenta

Yolk Sac

Extraembryonic structure providing early nourishment
Involved in blood cell formation

Blastocyst

Fluid-filled cavity in the morula
Separates cells into trophoblast and inner cell mass

Zona Pellucida

Glycoprotein layer surrounding the egg
Disappears during uterine implantation

Endometrial Lining

Lining of the uterus; blastocyst implants

Stomodeum/Stomatodeum

Depression in the ectoderm for mouth formation

Chorion

Outermost membrane surrounding the developing embryo; forms placenta

Mandible

Lower jawbone; crucial for facial development

Pharynx

Throat region; forms mouth and respiratory system

Groove

Depression or indentation in a structure
Involved in tissue or organ formation

Cheeks

Parts of the face beside the mouth; involved in facial development

Primitive Cells/Primitive Streak

Early stages of embryo development

Pharyngeal Arches

Tissue bands for early development;
Give rise to head and neck structures (jaws, ears, throat)

Cheiloschisis (Cleft Lip)

Condition where upper or lower lip does not form properly

Micrognathia

Abnormally small jaw

Macrognathia

Abnormally large jaw

Agnathia

Congenital absence of jaw

Microstomia

Abnormally small mouth

Astomia

Complete closure of the mouth

Oblique Facial Cleft

Slanted cleft extending from mouth to cheek

Aprosopus

Face lacks features

Craniosynostosis

Premature closure of skull sutures

Treacher Collins Syndrome

Genetic disorder causing underdeveloped facial bones/tissues

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Description

Explore the fascinating stages of embryogenesis, including cleavage, gastrulation, and neurulation. This quiz covers key concepts such as the formation of germ layers, the blastula, and the role of the amniotic cavity in early development.