Spermatogenesis
The process of formation of sperms is called spermatogenesis. It involves 3 phases- multiplication phase, growth phase, maturation phase.
- In multiplication phase, male germ cells also called as spermatogonia undergo mitotic divisions to form large number of spermatogonia.
- In growth phase, spermatogonia increases their size by accumulation of nutrition in the cytoplasm and are ready for meitoic division and the spermatocytes are called as primary spermatocytes with 46 chromosomes.
- In maturation phase- A primary spermatocyte completes the first meiotic division leading formation of two equal, haploid cells called secondary spermatocytes, which have only 23 chromosomes each and the secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids
Spermiogenesis-
- The spermatids are transformed into sperms, also called as spermatozoa by the process called spermiogenesis.
- After spermiogenesis, sperm heads become embedded in the Sertoli cells and are released from the seminiferous tubules by the process called spermiation
Fi. Spermatogenesis
Hormonal control of spermatogenesis
- Spermatogenesis starts at the age of puberty due to significant increase in the secretion of gonadotropin releasing hormone (GnRH) from hypothalamus.
- The increases level of gonadotropin releasing hormone stimulates the anterior pituitary to secrete luteinizing hormone(LH) and follicle stimulating hormone(FSH).
- LH acts at the Leydig cells and stimulates synthesis and secretion of androgens.
- Androgens stimulate the process of spermatogenesis.
- FSH acts on the Sertoli cells and secrete two factors- androgen binding protein (ABP) and inhibin which helps in spermiogenesis.
