Fetal Leydig cells in buffalo testis: Light and electron microscopic study

The present study was conducted on testis of 20 buffalo fetuses ranging from 2.5 cm to 20 cm curved crown rump length (CVRL). The tissues were processed for light and transmission electron microscopic study. The intertubular tissue was filled with primitive mesenchymal cells, developing Leydig cells and blood vessels. At 7.5 cm CVRL, some of the interstitial mesenchymal cells started developing into foetal Leydig cells and were androgen positive. These cells were characterized by their polygonal shape, eosinophilic cytoplasm and darkly stained spherical nucleus with prominent nucleoli at 9.5 cm CVRL. At 15.5 cm CVRL, the fetal Leydig cells were present in groups around the interstitial blood vessels, which increased in number and size at 20 cm CVRL and decreased afterwards. By TEM, three types of Leydig cells were observed at 14.5 cm CVRL as stem Leydig cells (Leydig cell A), progenitor Leydig cells (Leydig cell B) and immature Leydig cells (Leydig cell C). Leydig cell A had elongated nucleus with a very thin rim of cytoplasm. Leydig cell B had oval nucleus with comparatively larger amount of cytoplasm. Leydig cell C had adult Leydig cell like features and had round to oval nucleus with lager amount of cytoplasm. The cytoplasm of these cells contained mitochondria with elongated cristae, Golgi apparatus and very few lipid inclusions. The number and size of Leydig cells increased during early prenatal life.