Vertebrate Development

Human Oocyte

Fertilization

Fig Basal body (centriole) Sperm head Sperm-binding receptors Acrosome Jelly coat Vitelline layer Egg plasma membrane Hydrolytic enzymes Acrosomal process Actin filament Sperm nucleus Sperm plasma membrane Fused plasma membranes Fertilization envelope Cortical granule Perivitelline space EGG CYTOPLASM

Zygote Zona Pellucida Nucleus Cytoplasm

Fig Blastocoel Trophoblast Uterus Endometrial epithelium (uterine lining) Inner cell mass “Implantation” in Placental Mammals

Fig Trophoblast Hypoblast Maternal blood vessel Expanding region of trophoblast Epiblast “Implantation” in Placental Mammals

Fig Yolk sac (from hypoblast) Hypoblast Expanding region of trophoblast Amniotic cavity Epiblast Extraembryonic mesoderm cells (from epiblast) Chorion (from trophoblast)

hCG Human Chorionic Gonadotropin Maintains the corpus luteum so estrogens and progesterone maintain the endometrium. Inhibits the ant. Pituitary from releasing FSH and LH, halting the ovarian cycle Indicates early pregnancy via early pregnancy tests.