When and why does occlusion of the vas deferens affect the testis?

The motility of spermatozoa from successive segments of human and animal epididymides was examined under the phase-contrast microscope. The segments were taken from laboratory rodents unilaterally vas ligated for three to five months and from human orchiectomy specimens. Evidence for testicular alteration, caused by epididymal stasis proven by the phase-contrast motility profile, was sought by weight, gross observation, and histologic examination. Two observations were made on the animals: (1) the ligature about the vas seldom resulted in epididymal stasis because the ligature cut through the muscular wall of the vas (permitting a leak);and, (2) when stasis was achieved, gross and microscopic alterations of the testis from the normal were inevitable. The observations of the human material showed that a progressive loss of sperm motility during passage through the epididymis occurred in more than one half the specimens. The motility profile of these epididymides closely resembled that seen in the unilaterally vas-ligated animals. The suggestion is made that senescence of a testicle may be caused by occlusion of its excurrent ducts. These observations seemed to support the hypothesis that faulty sperm transport and faulty maturation, becuase of epididymal rupture and fibrosis (rather than the presence of autoantibodies to sperm) probably cause the unreliability of vasovasostomy. Storage of frozen semen offers more certainty than the possibility of successful vasovasostomy.