Spermatogenesis:

1. The process of sperm formation from the sperm mother cells of testis (male gonad) is called spermatogenesis.

2. It starts at puberty (14-16 years).

A. Multiplicative Phase

3. The epithelial cells present on the inner wall of seminiferous tubule multiply by mitotic division to form large number of spermatogonia (2N).

4. Some of the spermatogonia serve as stem cells for spermatogenic lineage.

5. Other spermatogonia function as progenitor cells or the precursors of spermatozoa.

B. Growth Phase

6. Some of spermatogonia (2N) undergo changes by accumulating food materials and grow almost double in size and become the primary spermatocytes (N).

C. Maturation phase. Each primary spermatocyte undergoes the first meiotic division and forms two haploid secondary spermatocytes (N).

7. The secondary spermatocytes undergo the second meiotic division leading to the formation of four equal-sized, haploid spermatids (N).

D. Spermiogenesis or Spermiation

8. The spermatids are transformed into spermatozoa by the process of spermiogenesis.

9. The sperm heads become embedded in the Sertoli cells and are ultimately released from the seminiferous tubules by the process of spermiation.

10. The spermatogenesis is under the control of follicle stimulating hormone (FSH) secreted by anterior lobe of pituitary.