Mast cells and fibrosis on testicular biopsies in male infertility.

Testicular dysfunction correlates with increased testicular mast cells. Mast cells can activate fibroblasts and promote collagen synthesis. The aim of the study was to examine testicular mast cells containing tryptase, and the relationship between mast cells and different fibrosis stages of interstitium and peritubular region of testes. Testicular biopsies obtained from 33 infertile men were assigned to 2 groups: normal spermatogenesis (n = 10) and defective spermatogenesis (n = 23). Total, interstitial, and peritubular mast cells were examined immunohistochemically using antihuman tryptase. The fibrosis stage was evaluated using vimentin and alpha-smooth muscle actin. The ratio of tubules with sclerosis to total tubules was also calculated. In all cases, mast cells were mainly localized in the interstitium. The number of total mast cells was significantly higher in defective spermatogenesis than in normal spermatogenesis (p = .048). In both groups, interstitial mast cells were higher than peritubular mast cells. However, the increase in peritubular region was much higher than the increase in interstitium. Total, peritubular, and interstitial mast cell counts were not different from each other, according to the changing fibrosis stages. Total and interstitial mast cells were significantly higher in the cases with sclerosing seminiferous tubules than in the cases with no sclerosis (p = .04 and p = .024, respectively). The mast cells and the mast cell product tryptase could be involved in the etiology of defective spermatogenesis, especially whenever the last stage (tubular hyalinization and sclerosis) takes place.