Specific localization of the basigin protein in human testes from normal adults, normal juveniles, and patients with azoospermia

Basigin is a transmembrane protein belonging to the immunoglobulin superfam ily. Specific localization of the protein in normal human testes, from thos e of a 2-year-old boy to those of a 50-year-old man, and in testes with Ser toli cell only syndrome and germ cell arrest, is reported. Basigin localiza tion was determined using an immunohistochemical technique with an antibody against human basigin. In the normal adult testes, basigin was detected at the periphery of both spermatocytes older than zygotene and round spermati ds. In the juvenile testes, it was expressed in accordance with the appeara nce of pachytene spermatocytes. In this study, pachytene spermatocytes were detected in an 11-year-old boy. Basigin was not expressed in immature test es with germ cells younger than pachytene spermatocytes, namely in testes f rom boys aged 2-9 years. In testes from adult patients with Sertoli cell on ly syndrome, basigin was expressed at the periphery of Sertoli cells, but l ocalization was confined to the adluminal compartment of the seminiferous t ubule. In testes with germ cell arrest, the protein was expressed on germ c ells from pachytene spermatocytes to step 2 spermatids, where present. The results show that in the normal human testes basigin is expressed with the onset of spermatocyte differentiation. Because human basigin is expressed i n adult testes with Sertoli cell only syndrome, the protein seems to be syn thesized in Sertoli cells and expression continues after these cells dediff erentiate in the seminiferous epithelium.