PSC 140 Lecture Notes - Lecture 3: Toxoplasmosis, Genital Herpes, Gonorrhea
Document Summary
Fertilization takes place in the fallopian tube. About 9th day attaches to uterine wall (by this time contains 100s of cells) Inner cell mass detaches & forms embryonic disc. About 25% of time there is a failure to implant (leads to miscarriage) Inner cell mass will eventually become the embryo, while the trophoblast will develop into membranes (ex: amnion, chorion -> placenta) that will protect & support the embryo. Wk 2 (after implantation) - wk 8. Ends when all major organs have developed in primitive form. After implantation the cells in the inner cell mass begin to differentiate. Skin, nails, teeth, lens of eye, inner ear, nervous system. Muscles, bones, circulatory system, ovaries/ testes, kidneys. Proximodistal: from middle of organism out to the periphery. Amnion - thin membrane that holds the amniotic fluid. Umbilical cord - links the placenta to the embryo. Screens many but not all harmful agents. Embryo is 1. 5 inches long (<0. 5 ounce)
