The influence of epididymal agenesis on the development and maturation of the testis: experimental model and clinical correlations.

The August X Copenhagen (ACI) rat provides an excellent model to study the effect of congenital epididymal anomalies on testicular function. Despite epididymal absence, testicular maturation and function are unchanged until puberty. At puberty, with increased testicular fluid and spermatozoa output, involution of germinal epithelium occurs. This involution is similar to the changes seen with ligation of the efferent ductules of the epididymis. These findings suggest that in this mammalian model the testis functions normally until the pubertal period. At that time, because of proximal epididymal agenesis and failure to reabsorb testicular secretions, intratesticular hydrostatic pressure increases with rapid germinal epithelial atrophy. Clinical correlations are made in patients with epididymal abnormalities, especially in association with undescended testis.