HUBS1404 Lecture Notes - Lecture 15: Adipose Tissue, Blastocyst, Meiosis
19 Jul 2018
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Document Summary
Stem cells (oogonia) divide by mitosis before birth to form oocytes: oocytes enter meiosis but are arrested in prophase i of meiosis. Meiosis i: arrested at prophase i before birth, completed after puberty, produces one fully mature egg. "first polar body" is very small and plays no part in the subsequent development: arrests in metaphase of meiosis ii. Meiosis ii: only completed if fertilisation occurs, 2nd meiotic division is unequal. "2nd polar body is very small and plays no part in subsequent development" Lh surge that triggers ovulation also triggers the maturation of the oocyte: process of meiosis only yields 1 oocyte, the other 3 are discarded. First trimester: embryological and early foetal development, developing a "body plan, rudiments of major organ systems appear. Second trimester nearly complete development of organ systems. Third trimester: rapid foetal growth, most organ systems become fully functional, deposition of adipose tissue.
