Disorders of Sexual Development of the Bull
Segmental aplasia of the mesonephric duct (SAMD)
The usual manifestation of segmental aplasia of the mesonephric duct is an absence of the body and tail of the epididymis. The head of the epididymis is also frequently missing and all that remains is a cystically distended region of the efferent ductules. The increased pressure in the rete testis and mediastinum results in dilation of the structures and testicular atrophy/degeneration. The ampulla of the deferent duct and the vesicular gland on the side of the missing segment are frequently small or missing.
Williams HJ, Revell SG, Scholes SF, Courtenay AE, Smith RF. (2010) Clinical, ultrasonographic and pathological findings in a bull with segmental aplasia of the mesonephric duct. Reprod Domest Anim. 2010; 45: e212-e216.
Spermatic granuloma of the epididymal head
The formation of spermatic granulomas in the head of the epididymis was first reported in bulls, and has been identified in most species. The cause is the failure of efferent ductules to join the mesonephric duct. Blind ended ductules fill with rete testis fluid and, if present, spermatozoa at puberty. Spermatoceles form and subsequently spermatic granulomas. This obstructs the other tubules causing rete testis fluid to accumulate and dilate the mediastinum. The testis swells.