QS Study

Spermatogenesis:

The process of formation and maturation of sperm from primordial germ cell in the male is tailed spermatogenesis. It is the production and development of sperm. This procedure begins at puberty and continues for the remainder of a male’s life. They are all derived from cells called stem cells in the outer wall of the seminiferous tubules.

  • Beginning: At puberty,
  • Duration: 64 days (germinal cell to sperm)
  • Site: The wall of the convoluted seminiferous tubules of testes.
  • Temperature: 32°C.
  • Rate of formation: 120 million / day.

Steps: Two steps.

Proliferative stage: Events are –

  1. Primordial germ cell gives rise to spermatogonia (44+XY). They are of two types. Type A divide by mitosis to provide and continuous reserve of stem cell and type B undergo mitosis and enlarges to form primary spermatocytes (44+XY).
  2. Primary spermatocytes undergo the first meiotic division to give rise to secondary spermatocytes (22 + x) and (22+Y). Here reduction of chromosome number occurs (Haploid number from diploid).
  3. Each secondary spermatocyte undergoes a second meiotic division to form spermatids (22+x) or (22+ Y). Here no reduction of chromosome occurs.

Maturation stage (Spermiogenesis):

Spermatids are transformed into spermatozoa. Changes include:

(i) Formation of acrosomal cap,

(ii) Condensation of the nucleus to form head,

(iii) Formation of neck middle piece and tail.

(iv) Shedding of most of the cytoplasm,

By this process, from one spermatogonium 512 spermatozoa are formed.