Testicular specific soluble antigens and spermatogenic onset in the mouse

Soluble antigens, specific for mouse testis, were detected by immunoelectrophoresis using a rabbit antiserum against a testicular extract (TE; supernatant of a mouse testicular homogenate spun at 105,000 g for 2 hr). At least 18 archs of precipitation were defined for the adult TE, but only three were testis specific. They were found in the epididymal extract, thus suggesting that these may be spermatozoal antigens. In immature mice, the testis-specific antigens start to appear in coincidence with the onset of pachytene spermatocytes. Immunohistochemical observations (peroxidase-antiperoxidase) showed specific reaction over spermatocytes and spermatids. The site of reaction was the surface or the peripheric cytoplasm of these cells.