BIO 189 Study Guide - Spermatogenesis, Meiosis, Gonadotropin
Document Summary
Although from puberty to old age sperm cells are constantly being engendered, the production is subject to extreme fluctuations regarding both quantity and quality. Four functioning, small (head 4 mm), motile spermatozoids at the end of the meiosis. During fetal period: no meiotic divisions + no germ cell production. Using up the oocytes generated before birth. Continual decrease of the oocytes, beginning with the fetal period. One large, immotile oocyte (diameter 120 mm) and three shriveled polar bodies are left at the end of the meiosis. During fetal period: entering into meiosis (arrested in the dictyotene stage) + production of the entire supply of germ cells: briefly describe the steps in reproduction in humans, produce the genetic material necessary for creating the offspring. Hypothalamus: gonadotrophin-releasing hormone controls secretion of luteinizing hormone and follicle- stimulating hormone in the pituitary. They can secrete testosterone and are often closely related to nerves. Testosterone is manufactured by the interstitial (leydig) cells of the testes.
