VGO 511: Veterinary Andrology and Reproductive Techniques (1+1)

INBREEDING, HYBRIDIZATION, FREEMARTINISM AND INTERSEXES

Inbreeding

• Generally results in reduced fertility accompanied by an increase in the number of abnormal seminiferous tubules, lowered semen quality and hypoplasia of testis.

Cytogenetic disturbances in spermatogenesis caused abnormalities in the primary spermatocytes including

• Stickness of chromosomes in which they failed to separate at anaphase and 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.
• In both condition the semen was thin and watery.

The male tortoise-shell cat

• It is rare and it may have an abnormal sex chromosome constitution of XXY resembling the more common Klinefelter’s syndrome in man.
• These male cats have small testes and are sterile due to failure of the seminiferous tubules to develop.

Infertility in hybrids

• Usually occurs when there are major difference in the chromosomes of the parents.
• Minor gene differences may be overcome so fertility is possible. A common example of the hybrid infertility is the horse and ass cross producing the hybrid mule with chromosome numbers of 64, 62 and 63.

Freemartinism

• Sometimes noninflammatory degenerative changes in the testis of the males born as a cotwin with the freemartin females are noticed.

Male intesexes

• They are invariably sterile.
• Male pseudohermaphroditism is found in the caprine, porcine and occasionally in bovine, equine and other species.

• True hermaphroditism is not common in domestic animals.

Intersexes in pigs are common but not as in goats.

• They also are of the male pseudohermaphrodite type.
• The cause is probably a recessive gene.
• The affected animals are genetic females, the testes are invariably intra-abdominal and externally a characteristic “fish hook” vulva with a prominent “clitoris” or phallus is observed in cattle, horses and dogs.