immuno-histochemical localization of endothelial nitric oxide synthase in testicular cells of men with non-obstructive azoospermia

background: non obstructive azoospermia (noa) is one of the causes of male infertility in which spermatogenesis process is disturbed. recent studies suggested the possible role of endothelial nitric oxide synthase (enos) in spermatogenesis process. objective: the aim of the present study is to evaluate the expression of enos in human testicular tissue in men with noa and men with normal spermatogenesis by using immunocytochemistry. materials and methods: in this case-control study, testicular biopsies were obtained from 10 men with noa and 7 men with normospermia who were attended to infertility center for diagnosis or infertility treatment. immunohistochemistry was used to localize the isoform of enos in these tissues and the intensity of staining was semi quantitively assessed. in addition, the histopathological evaluation was examined in both groups. results: the isoform of enos enzyme activity was detected in the cytoplasm of sertoli and leydig cells in both groups. there was, however, a considerable variability in the intensity of staining between two groups. the expression of enos in leydig cells in control group was significantly (p<0.05) higher than those in the noa group. in contrast, expression of enos in sertoli cells in noa was more than those in the control group. eno simmune staining was absent in the normal germ cells but was intense in the abnormal germ cells with piknotic neucleous. the most histopathological finding were hypospermatogenesis (27.2%), sertoli cell only syndrome (18.1%) and tubular fibrotic (13.6%). conclusion: these results suggested that increase level of enos may play an important role in the apoptosis process in the abnormal germ cells and disturbance of spermatogenesis process.