Abstract
The distribution and activity of the enzymes 20α-(20α-HSD) and 20β-hydroxysteroid dehydrogenases (20β-HSD) were studied histochemically in the ovary of the cattle, pig, crossbred pig×wild boar, sheep and goat. In the ovary of the cattle, pig and crossbred pig×wild boar, 20β-HSD activity was only trace to slight in the granulosa cells and theca interna of antral follicles and slight to weak in the corpus luteum, and no 20α-HSD activity was observed. In the ovary of the sheep and goat, 20α-HSD activity was only trace to slight in the granulosa cells and theca interna of antral follicles and slight to weak in the corpus luteum, and no 20β-HSD activity was present. It appeared that there were almost no differences in these enzyme activities in the ovary among different breeds within the same species and among stages of the estrous cycle. No 20α- and 20β-HSD activities were observed in the surface epithelium, ovarian stroma and theca externa of follicles in farm animals used. No activities of these enzymes were also observed in preantral follicles and atretic follicles. These findings suggest that the corpus luteum and granulosa cells and theca interna of antral follicles are likely to contribute to metabolism of progesterone to 20α- or 20β-dihydroprogesterone in the ovaries of these farm animals.
