Cyclic changes of steroid production activity in the ovary and estradiol levels in the blood plasma of the mudfish, Labeo capensis

The annual reproductive cycle of female Labeo capensiswas investigated using histochemical and endocrinological parameters. It was found that steroid production occurred in three localities in the ovary, namely, special theca cells, granulosa cells and interstitial cells. The 3β-HSD activity (steroid activity) in the granulosa cells and estradiol-17β concentration in the plasma reached a peak during exogenous vitellogenesis. During the oocyte maturation phase the 3β-HSD activity in the special theca cells and the GSI reached a maximum. Possible functions of steroids secreted by special theca cells and granulosa cells are discussed.S. Afr. J. Zool. 1987,22(3