The double nucleus of the sertoli cell in the lizard Anolis carolinensis

Over 90% of the Sertoli cells in the testes of adult lizards (Anolis carolinensis) are binucleate. The nuclei occur in closely associated pairs in the basal cytoplasm of the Sertoli cells that line the testis tubules. The two nuclei of a pair are of similar volume, and each usually contains one conspicuous rounded nucleolus. The average volume of individual nuclei varies from 367.8 microm(3) in spermatogenically active testes in March to 172.5 microm(3) in September, when testes are regressed. The irregular shape of the Sertoli nuclei is particularly pronounced during testicular regression. Until initiation of spermatogenesis in hatchling lizards, Sertoli cells have a single nucleus containing patches of hetcrochromatin. With the appearance of prophase stages of primary spermatocytes, a few paired Sertoli nuclei can be found, and the nuclei increasingly exhibit the homogeneous euchromatic nucleoplasm of the adult. The average volume of individual nuclei in lizards under 4 months of age is less than a third the volume of Sertoli nuclei in reproductively active adults. The appearance of binucleate cells at this time documents a doubling of the amount of desoxynucleic acid in Sertoli cells preparatory to their growth and expanded functions during spermatogenesis.