16 Questions
During the third week of gestation, what is the most characteristic event that occurs?
Gastrulation
What is the first indication that a woman may be pregnant?
Cessation of menstruation
What does gastrulation establish in embryos?
The three germ layers (ectoderm, mesoderm, and endoderm)
At what point can a normal pregnancy be detected with ultrasonography?
Approximately 5 weeks after conception
What is the name of the cavity formed during the third week of development that will surround the developing embryo?
Amniotic cavity
What is the beginning of morphogenesis and formation of the three germ layers in embryos called?
Gastrulation
What is the cephalic end of the streak referred to as?
Primitive node
What is the inward movement of cells beneath the epiblast known as?
Invagination
Which factor controls the migration and specification of cells during embryonic development?
Fibroblast Growth Factor (FGF8)
What does the embryonic ectoderm give rise to?
Epidermis, nervous systems, and neural crest cells
What does the embryonic endoderm give rise to?
Epithelial linings of respiratory and alimentary tracts, and glandular cells
What does the embryonic mesoderm give rise to?
Skeletal muscles, blood cells, and extraembryonic mesoderm
What covers the yolk sac and amnion?
Extraembryonic mesoderm
Where is the prechordal plate located?
Between the tip of the notochord and the oropharyngeal membrane
What does the oropharyngeal membrane consist of?
Tightly adherent ectoderm and endoderm cells without mesoderm
What is the notochord derived from?
Epiblast and hypoblast
Test your knowledge of the third week of embryonic development with a focus on the trilaminar germ disc and related structures such as amniotic cavity, extra embryonic coelomic cavity, and extra embryonic mesoderm.
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