Veterinary Andrology and Reproductive Techniques

Pathological factors

VI: PATHOLOGICAL FACTORS AFFECTING SPERMATOGENESIS

• The pathological factors affecting spermatogenesis are divided into two namely congenital factors and acquired factors.

Congenital factors

• Testicular hypoplasia: It is congenital or hereditary in origin caused by single recessive autosomal gene with incomplete penetrance leading to lack of meiotic division and block in spermatogenesis.
• Cryptorchidism: Spermatogenesis is inhibited by elevation of temperature of the affected testis. The affected testis is usually small in size, soft, flaccid and do not produce any spermatozoa.
• Imperfect descent of the testes: thermoregulatory system is affected and hence spermatogenesis is impaired.
• Scrotal or inguinal hernia: this interferes with the normal thermoregulatory mechanism and thereby affect the spermatogenesis.

Acquired factors

• Testicular degeneration: Several factors like heat, cold, trauma, excessive physical strain, unilateral castration, irradiation, fever, toxaemia, hot environment, insect bites on the scrotum, diseases like foot and mouth and other viral diseases, vaccination against rinderpest and FMD, Vitamin A deficiency, injection of autologous or homologous testicular material can cause testicular degeneration. Here, spermatogenesis is affected and there will be presence of spermatocytes in the semen. The seminiferous tubules are reduced in size.
• Testicular fibrosis: A marked degenerative change in the germinal epithelium together with increased interstitial tissue is noticed. Semen is usually watery containing few or no sperms.

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