Leydig cell heterogeneity as judged by quantitative cytochemistry of 3β-hydroxysteroid dehydrogenase activity in individual rat Leydig cells

3β-Hydroxysteroid dehydrogenase (3β-HSD) is one of the key enzymes involved in the steroidogenic pathway of Leydig cells. In this study, quantitative cytochemistry was used to detect the 3β-HSD staining intensity in individual rat Leydig cells. The measurement of the intensity of staining was a reliable method reflecting the relative amount of 3β-HSD activity. The objective was to determine the presence, basal and hCG-mediated effect of 3β-HSD activity in individual Leydig cells. 3β-HSD cytochemistry was performed in both, 8 and 12 μm diameter rat Leydig cells. The results showed that both populations of Leydig cells have different basal 3β-HSD activity. The 8 μm cells showed a greater basal 3β-HSD activity than the 12 μm cells when their optical density values were normalized to their size. A difference in regulation of the enzymatic activity by LH/hCG was observed in the two types of Leydig cells. Incubation of the whole population of Leydig cells with hCG (1IU), decreased the 3β-HS