Vasectomy and vasovasostomy. I. Timing of histologic changes in immature and mature dog testis after vasectomy.

The effects of vasectomy on the development and maintenance of spermatogenesis was studied using immature and mature dog testes. Bilateral vasectomy in immature dogs delayed the development of advanced spermatocytes, spermatids, and spermatozoa for about 3 months postsurgery. Spermatogenesis appeared to be recovered to control levels by 4 months postvasectomy. Spermatogenesis in mature dogs was also altered after bilateral vasectomy. Decreased numbers of advanced spermatocytes as well as maturation arrest was observed by 3 weeks postvasectomy. Seminiferous tubule cell layers quickly decreased to one to three layers as the lumina became occluded with sloughed cells by 3 to 6 weeks postvasectomy. Recovery in terms of the numbers of spermatocytes, spermatids, and spermatozoa was evident by 13 weeks postvasectomy, although occasional dog testes did not recover and appeared to be more sensitive to vasectomy-induced damage. It thus appears that vasectomy temporarily inhibits both the development and maintenance of spermatogenesis in immature as well as mature dog testes. Spermatogenesis does recover but may be maintained at somewhat lower levels after vasectomy. Changes are rapid in onset and take several weeks to be reversed. Some dog testes appear to be more sensitive to the damage and it may be irreversible in these testes.