What is Spermatogenesis?

Spermatogenesis starts at the age of puberty. These are the marked changes that are under the control of the following hormones.

• GnRH (Gonadotropin releasing hormone): At the time of puberty, a significant increase in the level of the hypothalamic hormone GnRH. The increased level of GnRH acts as a signal on the anterior pituitary gland, ultimately producing two gonadotropin hormones: 
  • Luteinising hormone (LH)
  • Follicle-stimulating hormone (FSH)
• Luteinising Hormone (LH): LH is known to act on the Leydig cells, which results in the secretion of androgens that ultimately stimulates the process of spermatogenesis.  
• Follicle-stimulating hormone (FSH): The secretion of FSH results in the release of various factors by Sertoli cells (nurse cells) which helps in the process of Spermiogenesis. 

The process of the formation of sperm starts with the division of diploid cells (2n or 46 chromosomes), which ultimately results in the formation of a haploid (n/ 23 chromosomes) spermatozoa (sperm). This process completes by the completion of the following two processes. 

Spermatogenesis

The diploid spermatogonia (singular-spermatogonia) cells are present inside the seminiferous tubules and multiply by the process of mitotic division and increase their number. Some of the spermatogonia cells get mature and become primary spermatocytes(2n).

1. The primary spermatocytes(2n) periodically undergo the meiotic division and produce the haploid secondary spermatocytes(n) after completing the first meiotic division. 
2. The secondary spermatocytes(n) complete the second meiotic division and produces four haploid cells known as spermatids. 

Spermiogenesis

It is the process of transformation of a spermatid into mature spermatozoa, also known as sperm cells. 

After completion of both the Spermatogenesis and spermiogenesis, the sperm heads become embedded in the Sertoli cells, and they finally get released into the seminiferous tubules by the process called spermiation.

Gametogenesis is a process of producing male and female gametes, carried out by all sexually reproducing organisms. The process involves various multiple stages of division and differentiation and is highly regulated under hormonal control.