Anatomy and Physiology 16.4a Oogenesis and the Ovarian Cycle Rated A+

Anatomy and Physiology 16.4a Oogenesis and the Ovarian Cycle Rated A+ oogenesis ova (female gametes) are produced oogonia(2n) the female stem cells, multiply rapidly to increase their number, producing daughter cells called primary oocytes primary oocytes 1. then push into the ovary connective tissue, where they become surrounded by a single layer of cells to ultimately form the primordial follicles, which grow to become primary follicles. 2. Does not exist by birth 3. no longer exist by birth 4. a female’s lifetime supply of primary oocytes (approximately 1 to 2 million of them) is already in place in the ovarian follicles 5. wait is a long one—usually from 10 to 14 years At puberty, the anterior pituitary gland begins to release FSH (follicle-stimulating hormone), which stimulates a small number of primary follicles to grow and mature each month, and ovulation begins to occur each month. Ovarian Cycle Monthly cycle of follicle development, ovulation, and corpus luteum formation in an ovary. As a follicle prodded by FSH grows larger It accumulates fluid in the central chamber called the antrum. the primary oocyte it contains replicates its chromosomes and begins meiosis The first meiotic division produces two cells that are very dissimilar in size 1. The larger cell is a secondary oocyte, 2. very tiny, cell is a polar body secondary oocyte - protrudes from the external surface of the ovary - is still surrounded by its follicle-cell capsule, now called the