Electron Microscopic Study of the Localization of Labeled Gonadotropins in the Sertoli and Leydig Cells of the Rat Testis

SummaryAdult male rats were intravenously injected with a single dose of FSH-Fe or LH-Fe; ferritin alone, unlabeled-hormones plus ferritin, denatured labeled hormones, and homologous albumin similarly labeled were used as controls. Electron microscopic studies of testis from rats injected with FSH-Fe demonstrated a predominant accumulation of the ferritin particles in vesicles and dense bodies of the Sertoli cell cytoplasm. After the injection of LH-Fe, the ferritin molecules appeared predominantly in the same organelles of immature Leydig cells, in peritubular structures, and in lesser amount in vesicles of Sertoli cells. The injection of control preparations resulted in fewer ferritin particles detected in the pertibular tissue and occasionally in Leydig or Sertoli cell cytoplasms.