A. Sperm Formation

1. Diploid spermatogonia undergo mitosis >>> primary spermatocytes, which undergo meiosis I >>> haploid secondary spermatocytes, which undergo meiosis II >>> haploid spermatids >>> mature sperm.

2. Sertoli cells in the tubule provide nourishment and chemical signals to the developing sperm.

3. Each sperm has a head (nucleus—DNA and acrosome), midpiece (mitochondria), and tail (microtubules of the flagellum).

B. Hormonal Controls

1. Testosterone, produced by Leydig cells located between the lobes in the testes, stimulates spermatogenesis, the formation of reproductive organs and secondary sex characteristics, and helps to develop and maintain normal (or abnormal?) sexual behavior.

2. Luteinizing hormone (LH) is released from the anterior pituitary (under prodding by GnRH from the hypothalamus) and stimulates testosterone production.

3. GnRH also causes the pituitary to release FSH, which stimulates the production of sperm, beginning at puberty.