Veterinary Andrology and Reproductive Techniques

Genetic factors

V: GENETIC FACTORS AFFECTING SPERMATOGENESIS

• Heredity sperm production is grossly affected by genetic abnormality like testicular hypoplasia and congenital aplasia of wolffian duct. Testicular hypoplasia in cattle is due to single recessive autosomal gene with incomplete penetrance. Hereditary defects in sperm production or maturation cause abnormality of the acrosome and separation of the head and tail.
• Inbreeding: it increases the abnormal seminiferous tubules and hypoplasia which will affect the spermatogenesis. This may be due to autosomal recessive gene.
• Cytogenetic disturbances: This causes two abnormalities in the primary spermatocytes including
  • Stickness of chromosome in which they failed to separate at anaphase
  • a pyknotic nucleus and multiple spindle formation due to a dysfunction of the mechanism of cell division due to extra centrosome divisions resulting in the formation of giant cells with a number of nucleus.
• Hybridization
  • Eg. Donkey(Jack) X Horse (mare) = Mule
    (62) (64) (63)
• The germ cells of hybrids proceed through mitosis, but there is a block to meiosis since ‘pairing’ of homologous chromosomes is impossible due to ‘uneven chromosome number’ having come from parents with different chromosome numbers.
• Freemartinism: In this condition there will be non inflammatory degeneration of testes which will affect the spermatogenesis.

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