Spermatogenesis after vasectomy.
Keywords: vasectomy, reversal, spermatogenesis, dogHistology of a canine testicle two years after vasectomy.
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To this author, apparently normal spermatogenesis was remarkable in the face of long standing vasectomy but indeed, it has been described before i.e:
"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." Urry et al. (1976)
There is little doubt that after vasectomy, fluid pressure, antibody formation, and sperm granulomas can disrupt spermatogenesis. Chronic distension of the ductus deferens can also compromise sympathetic tone of the ductus and its ability to contract and transport sperm during ejaculation. In some cases, especially in men who have been vasectomized for many years, spermatogenesis is severely compromised. Yet, in 40 to 80% of men, reversal of vasectomy will result in pregnancies without technological intervention.
It is not known how spermatogenesis continues after vasectomy despite the accumulation of sperm in the tract. In fact, seminiferous epithelium is healthy long after vasectomy in many individuals with tubules active and many actually showing spermiation.
More perplexing perhaps is the fate of sperm that are trapped within the testicles and epididymides. It has been suggested that sperm captured in the testicles and epididymides after vasectomy may dissolve after vasectomy. Apparently. this occurs in birds but in mammals, disulphide bonds in the nuclei, connecting pieces, sheath, tail fibers and mitochondrial shell, prevent dissolution and absorption of sperm. As discussed Bedford (1976) neither dissolving nor phagocytosis are principal mechanisms this process.
References:
Aaron M. Bernie et al. 2012 Vasectomy reversal in humans Spermatogenesis 2, Issue 4, 2012
Bedford J.M. 1976 Adaptations of the Male Reproductive Tract and the Fate of Spermatozoa Folowing Vasectomy in the Rabit, Rhesus Monkey, Hamster and RatBiol. Reprod. 14:18-142
Raleigh D et al. 2004. Testicular damage after vasectomy might impact upon the prospects for reversal. Fertil Steril. 81:1595-603.
Urry RL et al 1976 Vasectomy and vasovasostomy. I. Timing of histologic changes in immature and mature dog testis after vasectomy. Fertil Steril. 1976 Aug;27(8):937-44.
Yu Xiang et al. 2013 Long-term effect of vasectomy on spermatogenesis in men: a morphometric study. Asian J Androl. 15: 434–436.
Note: The author wishes to thank Dr C Love of TAMU for his assistance in this entry.
