Abstract
It was speculated that vasectomy might induce hyperplasia of Leydig cells associated with atrophy of seminiferous tubules, but estimates of the Leydig cell number were lacking in previous studies. This study aimed to test the speculation by determining the numerical change of Leydig cells and other interstitial cells after a vasectomy that induced spermatogenic damage. Twelve adult Japanese white rabbits and twelve mature Sprague-Dawley rats were subjected to a unilateral vasectomy away from the scrotum. Six months (rabbits) or thirty-seven days (rats) postoperation, testes on both sides were removed and methacrylate sections prepared. The total numbers (per testis) of all nuclei in the testicular interstitial tissue were estimated with a stereological technique – the optical disector. The results showed that marked spermatogenic damage associated seminiferous tubular atrophy on the vasectomized side occurred in 7 (rabbits) or 5 (rats) of the 12 animals. For the rabbit, the total numbers of myoid cells or leukocytes on the vasectomized side (compared with the contralateral nonvasectomized side) were unchanged but those of Leydig cells and other interstitial cells increased significantly by 41% and 52%, respectively, (a) with the increase in the testis with spermatogenic damage appearing to be larger than that in the testis without spermatogenic damage and (b) without significant increase in the total volume of the interstitium. For the rat, there were no significant differences in the total numbers of any cell type. In conclusion, hyperplasia or hyperproliferation of the interstitial cells, which might be a result of increased intra-testicular pressure for long, was possible postvasectomy, but it might not be indicative of a better function of the cells.
Highlights
In the 1920s, vasectomy was performed to rejuvenate older and fatigued men, assumed to be a result of atrophy of seminiferous tubules followed presumably by hyperplasia of Leydig cells in the inter-tubular interstitium which would presumably increase testosterone secretion [1,2,3,4,5]
It was recently suggested that vasectomy per se would not lead to spermatogenic damage, which would result in seminiferous tubular atrophy, unless increased intra-testicular pressure was induced when the reproductive tract could not accommodate or dispose of the spermatozoa and testicular fluid continually produced by the testis after vasectomy [17,18,19]
Since the estimation of total Leydig cell numbers per testis, which could be obtained with an unbiased counting technique – the stereological optical disector [20, 21], was lacking in previous studies, we speculated that the vasectomy-induced Leydig cell hyperplasia previously observed was a subjective impression on sections due to the tubular atrophy and a relative increase of the interstitial tissue, i.e. due to, more precisely, the increase of Leydig cell numerical density rather than the increase of absolute Leydig cell number
Summary
In the 1920s, vasectomy was performed to rejuvenate older and fatigued men, assumed to be a result of atrophy of seminiferous tubules followed presumably by hyperplasia of Leydig cells in the inter-tubular interstitium which would presumably increase testosterone secretion [1,2,3,4,5]. Since the estimation of total Leydig cell numbers per testis, which could be obtained with an unbiased counting technique – the stereological optical disector [20, 21], was lacking in previous studies, we speculated that the vasectomy-induced Leydig cell hyperplasia previously observed was a subjective impression on sections due to the tubular atrophy and a relative increase of the interstitial tissue, i.e. due to, more precisely, the increase of Leydig cell numerical density (relative number or number per unit volume of testis) rather than the increase of absolute Leydig cell number To test this speculation, the current study was carried out to estimate the total numbers of Leydig cells (nuclei), and other interstitial cells, with the sophisticated stereological method and compare the total numbers of cells in the testes on the vasectomized sides with those on the non-vasectomized sides using a unilaterally vasectomized rabbit model [18] and a unilaterally vasectomized rat model [19], either of which successfully brought about a vasectomy-induced spermatogenic damage in some animals
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