Reproductive System Question And Answers

Spermatogenesis.
Answer:

Spermatogenesis Definition:

• It is the process of formation of male gametes called spermatozoa from primitive germ cells (spermatogonia) in the testis.
• It takes place within the cytoplasm of the sertoli cells.

Spermatogenesis Stages:

1. Stage of proliferation.

• Each spermatogonia contains 22 autosomes and 1 sex chromosome either X and Y.
• During this stage, spermatogonia divides by mitosis.
• By this, chromosomal number remains unchanged.
• Out of 7 generations of spermatogonia in males, the last generation enters the next stage as primary spermatocyte.
• Spermatogonia migrate towards the lumen of seminiferous tubules.

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2. Stage of growth.

• Primary spermatocyte formed grows into large cells.

3. Stage of maturation.

• Each primary spermatocyte divides by meiosis which occurs in 2 stages.
• First – two secondary spermatocytes are formed
• Next, each secondary spermatocytes divides into two spermatids.
• Thus, total 4 spermatids are formed with half number of chromosome.

4. Stage of transformation.

• The spermatids formed are transform into matured spermatozoa called sperms.
• These sperms are then released into the lumen of seminiferous tubules.

Representation of process:

Spermatogenesis Duration:

• It takes on an average 74 days to form a mature sperm from a primitive germ cell.

Factors affecting spermatogenesis:

1. Hormones:

1. Follicle stimulating hormone (FSH)
   • Required for initiation of spermatogenesis Induces proliferation of spermatogonia
   • Stimulates formation of estrogen and androgen binding protein from sertoli cells.
2. Testosterone
   • Responsible for maintenance of spermatogenesis
3. Estrogen.
   • It is necessary for spermatogenesis
4. Luteinizing hormone (LH)
   • It is essential for the secretion of testosterone from leydig cells.
5. Growth hormone.
   • Required for proliferation of spermatogenesis.
6. Inhibin.
   • Regulates spermatogenesis by inhibiting FSH secretion.
7. Activin.
   • It increases secretion of FSH and accelerates spermatogenesis.

2. Sertoli cells:

• Support and nourish the germ cells.
• Supply all the necessary materials for spermatogenesis.
• Releases the sperms into lumen of seminiferous tubules.

3. Temperature:

• Increases in the temperature prevents spermatogenesis.
• The low temperature in scrotum is essential for spermatogenesis.
• The high temperature results in degeneration of seminiferous tubules and absence of spermatogenesis.

4. Infection:

• Infectious diseases causes degeneration of seminiferous tubules.
• This inhibits spermatogenesis.