BLG 10A/B Chapter Notes - Chapter 24: Tunica Vaginalis, Seminiferous Tubule, Androgen-Binding Protein
Document Summary
Only system necessary for species survival but not individual survival: not essential to the individual -- but impact species survival potential. Functions: development, maturation and nutritional support of gametes. Ie: progesterone, estrogen and testosterone ( steroid hormones are made of cholesterol) Surrounds by two tunics superficial tunica vaginalis = out-pocketing from peritoneum and tunica albuginea = fibrous capsule covering the testis. Tight-junctions between cells form the blood-testes barrier. Provide nutrients for sustenance ** for dividing sperm cells. Bathe developing sperm with testicular fluid rich in androgens and flushes sperm into lumen. Testosterone (formed by leydig cells) is converted to dihydrotestosterone and estradiol: germ cells divide and differentiate into sperm cells during spermatogenesis (fig 27. 9) Spermatogonia = between sustentocytes along basement membrane. Spermatocytes divide by meiosis (fig 27. 6, 27. 7) Undergo two divisions without a second duplication of chromosomes. Results in gametes with haploid chromosomal number (n)
