Specific surface antigens on rat pachytene spermatocytes and successive classes of germinal cells.

Ontogenesis and localization of surface antigens in spermatogenic cells have been demonstrated. Male Lewis/Wistar rats, inbred for more than 300 generations, were challenged with pachytene spermatocytes isolated from immature animals of the same strain. Serological tests of the resulting immunoglobulin (rat anti-rat pachytene spermatocyte IgG) were based on immunohistochemistry using fluorescein- or horseradish peroxidase-conjugated rabbit anti-rat IgG. For complementdependent cytotoxicity assays, rabbit heteroantiserum directed against rat pachytene spermatocytes was employed. Challenge of inbred rats with pachytene spermatocytes resulted in the formation of antibodies (rat anti-rat pachytene spermatocyte IgG) which specifically bound to the surfaces of pachytene spermatocytes and all successive classes of germinal cells. This antibody preparation did not bind to somatic cells of any organ examined, including the testis, nor did it bind to germinal cells less advanced than pachytene spermatocyte. Rat anti-rat pachytene spermatocyte IgG, after absorption with spermatozoa from epididymides of Lewis/Wistar rats, did not bind to elongated spermatids or spermatozoa. However, the antiserum still specifically bound to pachytene spermatocytes and, to a lesser extent, to successive classes of germinal cells less advanced than early spermatids, and to residual bodies. The inbred animals challenged with pachytene spermatocytes also developed aspermatogenesis as part of the immunological response. The data are discussed in relation to the possible role of specific surface antigenic determinants on germinal cells in their interactions during differentiation.