Proto-oncogene activity in the testis of the lizard, Podarcis s. sicula, during the annual reproductive cycle.

Since proto-oncogenes play a central role in the regulation of cellular growth and differentiation, localization of MYC, FOS, and JUN proteins has been studied in the testis of the lizard, Podarcis s. sicula, during the annual reproductive cycle by immunocytochemistry using antisera against c-myc, c-fos, and c-jun products. MYC was localized in the nuclei of spermatogonia (SPG), I and II spermatocytes (SPC), and spermatids (SPT). Strong immunoreactivity was detected in Sertoli cells just prior to the onset of the early spring spermatogenic wave coinciding with the androgen peak. FOS protein was present in the nuclei of SPG and SPC. In SPG an exclusive nuclear localization was seen during the active spermatogenic period (February-March and September). A perinuclear localization was observed during other months. Immunoreactivity in Sertoli cells was also observed during the periods of active spermatogenesis. JUN protein was localized in the cytoplasm of SPG as well as in I and II SPC and was detected in the nuclei of I and II SPC during April and October when spermatogenic waves occur. These data suggest that proto-oncogene activities have regulatory roles in the spermatogenesis of the lizard.