Key Terms
Asexual
One parent, genetically identical offspring (clones). Fast, efficient, no mate needed.
Embryonic tissue is bipotential
Same cell group can become male or female structures.
Sperm path (memorize the sequence)
Seminiferous tubules → Epididymis (maturation) → Vas deferens → Ejaculatory duct → Urethra → out
Estradiol
Most potent and prevalent form of estrogen; produced by ovaries; regulated by LH.
Hormonal trigger
Estrogen causes uterine wall receptors for oxytocin to develop. Baby reorients head-down, pressing cervix.
Positive feedback loop
Contractions → more oxytocin release → stronger contractions. (One of the few positive feedback systems in the body.)
If labor stalls
Synthetic oxytocin (Pitocin) administered to restart.
IVF (in vitro fertilization)
Egg and sperm combined outside the body; embryo placed in uterus at 8-cell stage; may produce multiple embryos.
ICSI (intracytoplasmic sperm injection)
Single sperm injected directly into egg; used when IVF alone fails.
Zona pellucida
Glycoprotein layer protecting the mammalian egg.
Acrosomal reaction
Sperm binds zona pellucida → acrosome releases digestive enzymes → breaks through glycoprotein layer → sperm membrane fu
Cleavage
Rapid cell divisions of zygote with no increase in overall mass.
Differentiation
Stem cells express specific gene sets → become specific cell types. Process is regulated by cellular signaling cascades.