Seasonal changes in the histochemical localization of Δ⁵-3β-hydroxysteroid dehydrogenase in the ovary of the five-striped Indian palm squirrel, Funambulus pennanti (Wroughton)

Abstract

The localization of Δ⁵-3β-hydroxysteroid dehydrogenase (Δ⁵-3β-HSD) was histochemically studied in the ovary of the five-striped palm squirrel during the different phases of reproductive activity. The steroids pregnenolone, 17α-hydroxypregnenolone, dehydroepiandrosterone and androstenediol were used as substrates. The distribution of enzyme activity in the different cell types of the ovary was identical with all the four steroid substrates; intensity of the reaction was, however, weaker with 17α-OHP as compared with that obtained with the other steroids. Intense enzymic activity was observed in the interstitial tissue, theca interna, atretic follicles, and the corpus luteum; moderate activity was also seen in the granulosa cells of healthy follicles in the ovaries of all sexually active females. There was no Δ⁵-3β-HSD activity in the ovaries of very young females and only traces of diformazan granules were detected in the interstitial tissue of prepuberal females and of parous, quiescent females. The intensity of Δ⁵-3β-HSD activity is correlated with the uterine weights which were considered to be indicators of steroidogenic activity of the ovary.