Vertebrate Development

Human Oocyte

Fertilization

Fertilization

Fig. 47-3-5

Basal body(centriole)

Spermhead

Sperm-bindingreceptors

AcrosomeJelly coat Vitelline layer

Egg plasmamembrane

Hydrolytic enzymes

Acrosomalprocess

Actinfilament

Spermnucleus

Sperm plasmamembrane

Fusedplasmamembranes

Fertilizationenvelope

Corticalgranule

Perivitellinespace

EGG CYTOPLASM

ZygoteZona Pellucida

Nucleus

Cytoplasm

Fig. 47-16-1

Blastocoel

Trophoblast

Uterus

Endometrialepithelium(uterine lining)

Inner cell mass

“Implantation” in Placental Mammals

Fig. 47-16-2

Trophoblast

Hypoblast

Maternalbloodvessel

Expandingregion oftrophoblast

Epiblast

“Implantation” in Placental Mammals

Fig. 47-16-3

Yolk sac (fromhypoblast)

Hypoblast

Expandingregion oftrophoblast

Amnioticcavity

Epiblast

Extraembryonicmesoderm cells(from epiblast)

Chorion (fromtrophoblast)

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.