L33 Psych 321 Lecture Notes - Lecture 3: Embryonic Stem Cell, Programmed Cell Death, Heterochrony
Document Summary
A single cell the size of a period in your textbook. Aristotle favored epigenesis the emergence of new structures and functions during development. Nicolaas hartsoeker drew the idea that sperm had a preformed person already inside of it. He also was a forefather of the microscope. Germinal period beigns at conception, ends after about 2 weeks. Embryonic period begins after implantation, ends at end of 8th week. Fetal period- beings from 9th week to birth. By 15 weeks, fetus exhibits movement that we would actually see during birth. Outer cells constitute protoplast: then egg with implant in uterine wall, the germinal period, period lasts until implementation (~2 weeks, developmental processes, cell division, cleavage, aka cell division. Egg travels down fallopian tube, multiplying through mitosis. If implementation happens too soon, then the environment will not be prepared and the egg will die.
