01:119:116 Lecture 15: Reproduction II
29 Oct 2018
School
Department
Course
Professor
Document Summary
Oogenesis: prior to puberty, primordial germ cells (2n, in female embryo, mitosis, oogonium (plural=oogonia) (2n, formed during embryonic development. No new oogonia formed after birth: mitosis, primary oocyte (2n, begin meiosis. Arrest at prophase i: at birth, female has around 1-2 million primary oocytes, by sexual maturity, most primary oocytes have degenerated. Around 200,000 remain: remain dormant until puberty. Acted on by hormones: follicle, primary oocyte, zona pellucida- layer of glycoproteins, follicle cells - outermost protective barrier, during + after puberty, each month 6-12 follicles mature. Primary oocytes grow + follicle cells proliferate. After around 1 week, one follicle is larger than others + continues to grow: primary oocyte, completes meiosis i. 8-10 hours before release from ovary: cytokinesis is unequal. Daughter cells are unequal in size (1) polar body (n) Smaller cell disintegrates (2) secondary oocyte (n) Larger daughter cell enters into meiosis ii.
