BIOL3190 Lecture Notes - Lecture 6: Vas Deferens, Twin, Heredity
Document Summary
When does meiosis occur in humans: males- occurs in the seminiferous tubules of the testis. Males maintain a pool of mitotically active germ cells through their lifetime. Mature sperm will swim down the epididymis and ductus deferens before ejaculation. Meiosis in mammalian males begins after puberty. Stem cells line the perimeter of the tubule. As sperm mature, they move toward the central lumen and are released- process takes 3 weeks to a month. 4 gametes of the same size with different genetics are formed each time: females- meiosis starts before the baby is born. All future germ cells are present at birth. They will arrest in late prophase i: crossover has already occurred. In each menstrual cycle a small number of oocytes reenter meiosis. Generates one gamete (egg) the other 3 are tiny and die. Oocyte development resumes in the ovary after puberty. Oocytes are surrounded by large numbers of somatic cells within a follicle.
