Effect of long-term vasectomy on seminiferous tubules in the guinea pig

The little previous work on the influence of vasectomy on the guinea pig te stis has given controversial results. One group reports that the guinea pig suffers autoimmune orchitis while others claim damage may be mechanical. T o clarify the issue, this study compares the morphology of seminiferous tub ules 3 years after left unilateral vasectomy (8 guinea pigs) and control sh am operation (6 animals). Grossly, left and right testes following left-sid ed vasectomy were similar to controls and not significantly different in we ight. On histology, left and right experimental testes and the control mate rial showed various degrees of seminiferous tubular degeneration, including intraepithelial vesicle formation, loss of germ cells and intraluminal mac rophages. Although vesicle formation was striking in most testes, quantitat ive analysis indicated that it was more frequent in the ipsilateral testis following unilateral vasectomy. It seems that vasectomy had exacerbated an age-related phenomenon. Lymphocytic infiltration was seen in five of the le ft testes following vasectomy, in two of the corresponding right testes, bu t in none of the controls. Two vasectomized left testes, however, showed at rophic changes but no lymphocytic invasion. The results suggest that autoim mune orchitis follows vasectomy but that it may not be the primary cause of degeneration. Attempts to gain positive evidence for mechanical damage, ho wever, were inconclusive. (C) 1999 Wiley-Liss, Inc.