Offspring Development

Ovulation

Oocyte and corona radiata are expelledSwept into infundibulum of fallopian tube by fimbriaeFertilization may or may not occurPasses into uterus

2 Regions:BodyCervix

- opens into vagina by external os- cervical glands secrete mucus that blocks external os

3 layers:Perimetrium

- secretes serous fluidMyometrium

- muscular layerEndometrium

- epithelial and vascular layer

Remaining Anatomical Structures:

Vaginal Structures:Fornix: pockets around external osVaginal Orifice: external opening

Vestibular Glands:- secrete mucus for lubrication

Prenatal DevelopmentFertilization:

- in uterine tube- hyaluronidase from acrosomes

penetrates corona radiata and zona pellucida- zona pellucida “hardens”-oocyte continues meiosis- nuclei of sperm cell and egg cell

unite = zygoteBlocks to Polyspermy:1.) Fast Block

1 sperm contacts oocyte membraneNa+ channels open and Na+ enters

oocytemembrane depolarizes no other sperm can fuse with

membrane2.) Slow Block

ER releases Ca++signals cortical granules to release

enzymes into space beneath zona pellucida

sperm receptors are destroyedenzymes bind water, swelling layer

and forcing away other attached sperm from oocyte

Prenatal DevelopmentEmbryonic Period

Sperm nucleus travels towards ovum nucleusMitotic spindle forms Pronuclei degenerate and chromosomes formHomologous chromosomes attach to mitotic spindleMitosis continues and first cleavage completes

Prenatal DevelopmentEmbryonic Period

Mitosis continues until morula forms16 cells3-4 day journey to uterus

Blastocyst forms- cells are dividing and differentiating- two portions develop:Trophoblast = contributes to placentaInner Cell Mass = eventually forms embryo- Fluid fills intercellular space

between two layers = blastocyst cavity

Blastocyst is released from zona pellucida

Prenatal DevelopmentEmbryonic Period

Implantation begins around day 6 or 7-Trophoblast secretes enzymes that allow it to bury into endometrium

Prenatal DevelopmentEmbryonic Period

Embryo forms embryonic disc: cells on ventral side = endoderm cells on dorsal side = ectoderm

Primary germ layers - become baby’s tissues

Space between embryo and trophoblast = amniotic cavity (dorsal side)

Chorion - Forms from trophoblast- Later becomes part of

placentaAmnion-expands amniotic cavity until it surrounds embryo

Prenatal DevelopmentEmbryonic Period

Gastrulation:- Occurs during third week of

development- Endoderm depends on yolk sac- Primitive streak thickens along

embryo’s midline, folds inward = mesodermEmbryo = gastrula

Prenatal DevelopmentEmbryonic Period

Neurulation:- Mesoderm cells form rodlike

notochord- Ectoderm folds into neural tube

and neural crest- Embryo = neurula

Prenatal DevelopmentEmbryonic Period

Organogenesis: - Weeks 4-8- Further folding of all

layers results in body cavities and organs

Embryo is considered a fetus at about 9 weeks

Prenatal DevelopmentEmbryonic Period

Prenatal DevelopmentFetal Period