Effect Of Distal Vasectomy On The Spermatogenesis In The Rat: A Morphometric Study

Objective: To study the effect of distal vasectomy on thespermatogenesis in rats, thus clarifying the mechanism of vasectomy-induceddamage of spermatogenesis in the testis.Methods:12male Sprague-Dawley rats (aged10-11weeks) weresubjected to unilateral (left or right, randomly selected) vasectomy, with theposition of vasal ligation away from the epididymal tail and scrotal sac.37days after operation, testes, epididymides and vasa deferentia were removedand methacrylate resin-embedded sections prepared. Histological observationwas carried out; morphometric data such as the total volumes of keystructures in the organs were quantitatively studied using stereologicalmethods.Results: In7rats, the volume of testis on the vasectomized side, incomparison with the non-vasectomized side, was not significantly changed,the spermatogenesis was not markedly damaged, and the diameter of theseminiferous tubules was not significantly changed, but the total volume ofthe tubular lumen increased significantly by80.4%37.2%(mean sem);the total volume of the sperm mass in the epididymal duct did not increasesignificantly, but larger sperm granuloma (weight0.11-0.30g,0.180.03g)was formed at the place of vasal ligation. In the other5rats, the testicularvolume on the vasectomized side (compared to the non-vasectomized side)decreased by53.0%5.1%, marked damage to spermatogenesis occurred–with spermatids and spermatocytes depleted in43.3%10.0%of the tubular profiles, and the tubular diameter decreased by31.2%3.6%; the totalvolume of sperm mass in the epididymal duct decrease by90.1%5.6%;smaller sperm granuloma (weight0.02-0.12g,0.050.02), absent at theplace of ligation in1animal, was formed in4animals.Conclusion: Absence of spermatogenic damage after vasectomy in somerats was due to the fact that the formation of sperm granuloma relieved thepressure within the reproductive duct, while presence of spermatogenicdamage in some other rats was because sperm granuloma was not formed orwas too small, and the reproductive tract (including sperm granuloma) couldnot accommodate sperm and testicular fluid continually produced by the testis,thus resulting in increase of pressure within the reproductive tract (and testis).In conclusion, vasectomy-induced damage to spermatogenesis in the rat, wasintra-reproductive tract pressure-mediated.