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

SYMPTOMS

In most cases - sexual desire is excellent and coitus is prompt. Owners may not suspect the infertility for sometime.

• The degree of either unilateral or bilateral testicular hypoplasia varies from complete hypoplasia causing sterility to only slight softer unsuspected hypoplasia.
• Lowered conception rates are often evident in bilaterally affected males.
• Severe testicular hypoplasia is usually observed in young bulls of 1-2 years of age.
• In sterile bull with bilateral hypoplasia, the semen is usually clear, and watery with few or no spermatozoa.
• Centrifugation of the ejaculate and staining of the sediment revealed the presence of giant cells and medusa cells or ciliated cells from the efferent tubules.
• Giant cells or multinucleated cells with 6-8 nuclei apparently result from incomplete maturation division of the primary spermatocytes. These cells are seen in testicular hypoplasia and severe degeneration.
• Sexual organ develop normally except the affected testis.
• The consistency of the testes was soft, flabby or hard, indurated and fibrotic.
• Males which are severally affected are nearly sterile, but an occasional conception may occur in females bred to them.
• The semen picture shows a lower concentration of spermatozoa usually less than 70,000 per cmm, low motility, many abnormal spermatozoa and the possible presence of a few giant cells.
• Histologically the seminiferous tubules are very underdeveloped with usually only the basal layer of cells being present. Varying degrees of spermatogenesis may be present from spermatogonia, spermatocytes, spermatids to abnormal or normal mature spermatozoa.
• In some bulls with a moderate to slight amount of testicular hypoplasia the conception rate is low, about 20-40%. The testicles may appear nearly normal in size and consistency. The spermatozoa concentration is from 1,00,000 to 5,00,000 per cmm. The motility is usually low and the number of pathological or abnormal spermatozoa is high about 30% or greater.

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Epididymis

• Depending upon the degree of hypoplasia affected bulls will have a small firm epididymis especially in the tail region indicating reduced spermatogenesis and low gonadal sperm reserves.
• Spermatic cords of hypoplasia testicles are shorter as the testes are less heavy and the scrotum smaller than in normal males.

Slight or mild cases of testicular hypoplasia may predispose to testicular degeneration.

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