Effects of activin on DHP-induced steroid secretion. Various doses of human activin A (0–250 ng/ml), as indicated on the abscissa, were added to the culture media alone or in combination with a sub maximal dose of DHP (0.001 μg/ml). Follicles were also treated with higher doses of DHP (0.01 and 0.1 μg/ml) alone as positive controls. Oocyte maturation was monitored by scoring GVBD at 24 and 48 hr of incubation. Data are the mean ± SEM from 5 different experiments. Same letter indicates significantly different from each other at P ≤ 0.05.