Localization of retinol (vitamin A) in rat testes

The purpose of the study was to determine the intracellular location of exogenously injected labeled vitamin A (retinol) in rat testes by light and electron microscopic autoradiography. Tritium-labeled vitamin A mixed in vitamin A-free rat serum was injected intracapsularly in one testis in adult rats. At intervals of 30 minutes, 2 hours, and 4 hours following injection the treated testes were removed the processed for autoradiography. The results show that in the testes vitamin A is localized at three sites: within the macrophages of the interstitial tissue, in the lipid droplets of the Sertoli cells, and in the spermatids in association with Golgi saccules. To confirm the autoradiographic localization of vitamin A, the cellular retinol-binding protein (CRBP) assay demonstrates the presence of CRBP in the interstitial tissue and seminiferous tubules. The results of the study suggest a possible role of vitamin A in spermiogenesis in rat testes.