All flashcards
Flashcard 1: Identify the germ layer that forms the adrenal cortex.
Answer: Mesoderm. Intermediate mesoderm gives rise to urogenital structures including the steroid-producing adrenal cortex.
Flashcard 2: Which germ layer gives rise to the epithelial lining of the GI and respiratory tracts?
Answer: Endoderm. Innermost layer develops into internal linings and glands via epithelial folding.
Flashcard 3: Identify the germ layer that forms the adrenal medulla.
Answer: Ectoderm (neural crest). Neural crest cells migrate to form chromaffin cells of the medulla, producing catecholamines.
Flashcard 4: Which germ layer gives rise to the epidermis and nervous system?
Answer: Ectoderm. Outermost layer differentiates into external and neural tissues via inductive signals.
Flashcard 5: What is involution during gastrulation?
Answer: Rolling of a cell sheet inward over an internal surface. Allows cells to move interiorly along an internal surface, contributing to mesoderm formation.
Flashcard 6: What is invagination during gastrulation?
Answer: Inward folding of a cell sheet into the embryo. Creates internal cavities like the archenteron by bending epithelial sheets during layer formation.
Flashcard 7: What is the primitive streak in mammals?
Answer: A groove where epiblast cells ingress during gastrulation. Defines the embryonic axis and site for mesoderm and endoderm formation in amniotes.
Flashcard 8: What is implantation?
Answer: Embedding of the blastocyst into the endometrium. Occurs around day 6-7 post-fertilization, establishing maternal-fetal interface for nutrient exchange.
Flashcard 9: What is the morula stage of embryonic development?
Answer: A solid ball of cells formed after cleavage. Represents compaction of blastomeres before fluid accumulation leads to blastocyst stage.
Flashcard 10: What is the blastula (blastocyst in humans)?
Answer: A hollow ball of cells surrounding a fluid-filled cavity. Forms after cleavage and cavitation, preparing for implantation and gastrulation.
Flashcard 11: Which structure in the human blastocyst becomes the embryo proper?
Answer: Inner cell mass (embryoblast). Contains pluripotent cells that differentiate into all embryonic tissues during development.
Flashcard 12: Which structure in the human blastocyst primarily contributes to the placenta?
Answer: Trophoblast (outer cell layer). Differentiates into syncytiotrophoblast and cytotrophoblast, facilitating implantation and placental formation.
Flashcard 13: What is gastrulation?
Answer: Reorganization forming ectoderm, mesoderm, and endoderm. Establishes the three primary germ layers essential for organogenesis in triploblastic animals.
Flashcard 14: What process forms the blastocoel during blastulation?
Answer: Fluid accumulation creates a central cavity. Occurs as trophoblast cells secrete fluid, transforming the morula into a blastocyst.
Flashcard 15: What is the zygote in human development?
Answer: A diploid cell formed by fusion of sperm and oocyte. Results from fertilization, combining genetic material to initiate embryonic development.
Flashcard 16: What is a blastomere?
Answer: A cell produced by cleavage divisions of the zygote. Each is totipotent initially, contributing to the morula through successive cleavages.
Flashcard 17: What is cleavage in early embryogenesis?
Answer: Rapid mitotic divisions without overall embryo growth. Divides the zygote into smaller blastomeres while maintaining constant volume until blastula formation.
Flashcard 18: What is ingression during gastrulation?
Answer: Individual cells migrate inward from the surface layer. Facilitates individual cell migration to form new layers, as seen in primitive streak gastrulation.
Flashcard 19: Which germ layer gives rise to muscle, bone, blood, and kidneys?
Answer: Mesoderm. Middle layer forms supportive and connective tissues through segmentation and differentiation.
Flashcard 20: What is the blastopore?
Answer: The opening of the archenteron to the exterior. Becomes the anus in deuterostomes or mouth in protostomes, connecting archenteron externally.
Flashcard 21: What is the archenteron?
Answer: The primitive gut formed during gastrulation. Develops into the digestive tract lining through gastrulation movements in deuterostomes.
Flashcard 22: Which option correctly matches germ layer to derivative: liver parenchyma?
Answer: Endoderm. Hepatocytes derive from endodermal foregut diverticulum during organogenesis.
Flashcard 23: What is delamination in early embryonic development?
Answer: Splitting of one cell sheet into two parallel sheets. Separates cell layers without migration, often forming endoderm from hypoblast in some species.
Flashcard 24: Which embryonic structure induces overlying ectoderm to form neural tissue?
Answer: Notochord. Mesodermal structure secretes signaling molecules like Shh to pattern neural plate formation.
Flashcard 25: What is neurulation?
Answer: Formation of the neural tube from the neural plate. Involves ectodermal thickening, folding, and closure induced by notochord for CNS development.