What cells are totipotent in human development?
Cells from the zygote through the morula stage that can form both the embryo proper and extraembryonic tissues.
What developmental stage marks the loss of totipotency?
Formation of the blastocyst.
What cells are pluripotent in early development?
Inner cell mass (ICM) cells.
What can pluripotent cells form?
All body cell types but not extraembryonic tissues.
What structure gives rise to the embryo proper?
Inner cell mass.
What two layers form from the inner cell mass?
Epiblast and hypoblast.
Which structure gives rise to all three germ layers?
Epiblast.
Which structure primarily forms the yolk sac?
Hypoblast.
Which structure is responsible for implantation?
Trophoblast.
Which trophoblast layer secretes hCG?
Syncytiotrophoblast.
What developmental stage marks the loss of totipotency?
Formation of the blastocyst.
What cells are pluripotent in early development?
Inner cell mass (ICM) cells.
What hormone maintains the corpus luteum in early pregnancy?
Human chorionic gonadotropin (hCG).
What structure secretes progesterone in early pregnancy?
Corpus luteum.
What hormone directly maintains the endometrium?
Progesterone.
What is the endometrium?
The inner lining of the uterus that supports implantation and pregnancy.
What is the correct hormone cascade for maintaining pregnancy?
hCG → corpus luteum → progesterone → endometrium.
At what stage is the primary oocyte arrested before birth?
Prophase I.
At what stage is the secondary oocyte arrested?
Metaphase II.
What structure surrounds the mammalian oocyte?
Zona pellucida.
What reaction allows sperm to penetrate the zona pellucida?
Acrosome reaction.
What reaction prevents polyspermy?
Cortical reaction.
What is the first developmental event after fertilization?
Cleavage.
What is cleavage?
Rapid mitotic divisions without cell growth.
