Time course of increased ovarian 17,20β-P binding to mPR and oocyte maturation. Arctic char ovarian fragments were incubated with 14 IU hCG/ml. At the end of each incubation period, oocytes were examined for 17,20β-P binding and the occurrence of GVM and GVBD. Each bar represents the mean ± SEM from 5 different fishes, each one assayed in triplicate. * P < 0.01 compared to other time points.