Fine Structure of the Rabbit Epididymis and Vas Deferens after Vasectomy

Adult male rabbits were subjected to either bilateral vasectomy or a bilateral sham operation. Several portions of the epididymis and vas deferens were studied with the light and electron microscopes at intervals up to 9 months after operation. In vasectomized rabbits, the epididymis and proximal vas deferens were distended with sperm and expanded progressively from 2 weeks through 4 months after vasectomy. This expansion continued in one rabbit killed at 6 months and in one killed 9 months after vasectomy. However, in the remaining 3 rabbits killed 6 or 9 months after vasectomy, the epididymidis and vas deferens were less distended than in other vasectomized animals, and in 2 of these there was evidence that sperm escaped the male duct system and underwent phagocytosis in a spermatic granuloma in the surrounding connective tissue. Despite the distention, the epithelium of the epididymis and vas deferens of vasectomized rabbits remained columnar. The epithelium also continued to be functionally active as indicated by the persistence of the characteristic complement of cellular organelles, including vacuoles and lysosomes thought to be involved in absorption and smooth endoplasmic reticulum that may be involved in secretion. The epithelium of the cauda epididymidis and proximal part of the vas deferens in both vasectomized and sham-operated animals fixed 2 to 6 months after operation was highly folded and had many apical cytoplasmic projections. The origin of this change is unknown, but it may be related to seasonal variations in activity of the epithelium.