Ultrastructural and morphometrical analyses of Leydig and Sertoli cells in the testes of rats with hereditary polydactylism

摘要

Rats of the polydactylous (PD) strain carry an autosomal recessive gene pd that causes polydactylism in homozygotes (pd/pd). Male homozygotes are sterile owing to an abnormality of spermatogenesis. In the present study, Leydig and Sertoli cells of 12-week-old pd/pd male rats were examined for ultrastructural alterations in an attempt to clarify the cause of the abnormal spermatogenesis. The relative volumes of the organelles were also determined with morphometry. Phenotypically normal pd/+ males served as controls. No morphological or morphometrical abnormalities were noted in the Leydig cells. However, two different types of Sertoli cell were evident: light cells and dark cells. The incidence of the dark Sertoli cells in pdlpd males was high (27%) compared with that in pd/+ males (6%). These dark cells contained quantities of lipid droplets in the cytoplasm and exhibited a significant increase in the relative volume of lipid droplets compared with the value for the light cells. The nuclei of the dark Sertoli cells were irregular in shape and were invaginated. These results suggest that dark Sertoli cells may have lower lipid metabolism, and in pdlpd males, the high number of these dark Sertoli cells may be related to abnormal spermatogenesis.