Inhibin B in seminiferous tubules of human testes in normal spermatogenesis and in idiopathic infertility.

Inhibin B is one of the most significant serum markers of spermatogenesis, but its testicular expression has been poorly studied. Inhibin B sensitivity as well as the ability to reflect the level and condition of spermatogenesis and forecast certain changes in reproductive homeostasis in males is still a subject of active discussion. The purpose of this study is to examine the level of expression of inhibin B in cells of human seminiferous tubules in normal and in pathological spermatogenesis (idiopathic infertility) by revealing the proportion of immunostaining cells for inhibin B. The research conducted included analysis of testicular tissue samples taken from 82 males diagnosed with infertility and nonobstructive azoospermia. The influence of inhibin on the germ cells of men aged 22-35 been analyzed using the immunohistochemical method. According to the obtained results, high expression of inhibin can be detected both in Sertoli (98.0 ± 2.66) and Leydig (94.0 ± 1.55) cells in patients suffering from focal spermatogenesis disorders (mixed atrophy), in comparison with the men in the control group (65.9 ± 0.44 and 12.0 ± 0.44, respectively). The level of inhibin expression in the cytoplasm of spermatogonia was 4.0 ± 0.22 in control group of fertile men, while it was significantly increased in patients with Sertoli cell-only syndrome with focal spermatogenesis (45.0 ± 0.44). In the case of severe lesion to the seminiferous tubules (e.g., tubular hyalinization), the lowest level of inhibin expression in Sertoli cells is detected, whereas the immunostaining in Leydig cells showed only slight changes. Further histological research of Sertoli cells and inhibin B expression is necessary because, according to our data, the degree of inhibin B expression may be a useful marker of Sertoli cells function which can lead to new findings in the concept of local reproductive homeostasis in testis that may be impaired in some forms of idiopathic infertility in males. Abbreviations: β-TGF: β-transforming growth factor family; GCA: germ cell abnormalities/atypia; JS: Johnsen score; FSH: follicle stimulating hormone; TESE: testicular sperm extraction; LH: luteinizing hormone; F-Testo: free testosterone; ELISA: the enzyme-linked immunosorbent assay; CV: coefficient of variance; DR: range of definitions; AZF: azoospermia factorI; HC: immunohistochemical; HIER: heat induction of epitope retrieval; H&E: hematoxylin and eosin.