Immunostaining of transferrin and transferrin receptor in human seminiferous tubules

Transferrin (TF) and transferrin receptor (TFr) were studied in human testicular biopsy specimens with the use of immunostaining techniques. A polyclonal antibody to human TF (obtained in goat), a murine monoclonal antibody (B3/25) to human TFr, and antisera antigoat IgG and antimouse IgG, both labeled with peroxidase, were used. In seminiferous tubules of subjects with normal spermatogenesis, TF was found mainly in Sertoli cells and, in lesser amounts (probably related to the presence of receptor-TF complexes), in spermatocytes and early spermatids. TFrs were found only in spermatocytes and early spermatids. In patients with spermatogenetic disorders, TF was always found in Sertoli cells, whereas TFrs were found in spermatocytes only when they were present. These results seem to demonstrate that in human seminiferous tubules, Sertoli cells are devoted to the production and/or storage of TF, whereas spermatocytes and early spermatids use TF.