Embryo development Flashcards
Q: What are the two layers of the bilaminar embryonic disc, and which one gives rise to the embryo?
A: Epiblast and hypoblast. Epiblast gives rise to the entire embryo.
Q: What is the function of the primitive streak during gastrulation?
A: It’s the site where epiblast cells migrate inward, undergoing EMT to form the mesoderm and endoderm.
Q: Which germ layer replaces the hypoblast during gastrulation?
A: The endoderm (formed from epiblast cells) replaces the hypoblast.
Q: Name the three germ layers and one structure that each gives rise to.
A:
Ectoderm → skin or brain
Mesoderm → muscle or heart
Endoderm → gut or lungs
Q: A failure of the primitive streak to form would most directly prevent the development of what structure?
A: The three germ layers, and therefore the entire body plan.
Q: What is the role of the notochord in neural tube formation?
A: It signals the overlying ectoderm to thicken into the neural plate, initiating neurulation.
Q: Where does the notochord originate from?
A: The axial mesoderm (midline mesoderm).
Q: What structure is derived from the notochord in the adult human body?
A: The nucleus pulposus of the intervertebral discs.
Q: A baby is born with spina bifida. What process likely failed during Week 4?
A: Closure of the neural tube at the caudal end (lower spine).
Q: What layer does the neural plate arise from, and what does it become?
A: From ectoderm, becomes the neural tube → brain & spinal cord.
Q: Neural crest cells migrate from which germ layer and give rise to which types of structures?
A: They originate from ectoderm, and form cranial bones, peripheral nerves, melanocytes, etc.
Q: What is the stomodeum, and what does it eventually become?
“Stoma” = mouth
“Deum” = opening
A: The primitive mouth, it opens into the pharynx and becomes the oral cavity.
Q: What happens to the oropharyngeal membrane during facial development?
A: It breaks down to connect the stomodeum to the foregut/pharynx.
