CYTOCHEMICAL-LOCALIZATION OF THE NADPH DIAPHORASE ACTIVITY IN THE LEYDIG-CELLS OF THE MOUSE

The distribution of the NADPH diaphorase activity was studied in mouse Leydig cells by means of light and electron microscopy. When observed by the light microscope, most Leydig cells appeared intensely stained ; a few cells (about 10%) showed a slightly positive or apparently neg ative reaction. The inhibitory effects of N-G-nitro-L-arginine and iod onium diphenyl on frozen sections suggest the colocalisation of NADPH diaphorase reaction with nitric oxide synthase. The ultrastructural st udy revealed that all the Leydig cells were positively stained for NAD PH diaphorase; however, a small number of cells displayed weak enzymat ic activity. The reaction product was located in the mitochondria, smo oth endoplasmic reticulum and lipidic vacuoles, and the nuclear envelo pe was also stained. The possible meaning of the NADPH diaphorase acti vity in the Leydig cells of mice was discussed.