Immunological relationships between specific sperm proteins and secretory polypeptides from seminal vesicles

Rat and bovine testicular and posttesticular spermatozoa, in situ or removed from the seminal pathways were studied for the presence and the binding of seminal vesicle secretory proteins. A protein cross-reactive with an antibody against rat seminal secretory sulfhydryloxidase was found in mitochondria of pachytene primary spermatocytes which are sequestered during spermiogenesis and collected in the residual bodies of late spermatids. This indicates the replacement of one generation of mitochondria by another during spermiogenesis. Using an antibody against the SVS II polypeptide from rat seminal vesicles, an intrinsic immunoreactive protein was detected in the principal piece of the sperm tail as well as an extrinsic protein (presumably secreted by the epididymis) on the sperm head. The actin-capping capacity of SVS II indicates the functional relation of this immunoreactive membrane protein with actin or an actinrelated protein. Ampullary bovine spermatozoa, contrary to their epididymal precursors contain immunoreactive major protein, secreted from bull seminal vesicles, firmly incorporated into the (sub) plasmalemmal protein in the middle piece. In this case, a secretory protein from seminal vesicles is incorporated into the sperm proteins. This is presumably an important process, related with the initiation of hypermotility of spermatozoa.