Blockage of ducts
In some bulls there is a blockage of the transport of sperm through the epidydimis usually caused by a congenital non-patency of some part of the vasa efferentia. This results in accumulation of spermatozoa in the patent regions near the epididymal head leading to the formation of a palpable spermatocoel. Continued accumulation and development of a chronic back pressure results in degeneration of the spermatogenic epithelium.