Peripheral migration and the breakdown of the germinal vesicle occur during the penultimate stage of oocyte maturation, which follows the conclusion of the vitellogenic growth phase (GVBD). The effects of cynoketone, actinomycin D, cycloheximide and froskolin on spontaneous and progesterone- induced and of the ophyllins on toad-pituitary extracts induced oocyte maturation were investigated during the study. The addition of TPA to the incubation media at concentrations of 0.01 - 10µM induced GVBD in a dose dependent manner. At the end of 48 hrs of incubation 100% GVBD had occurred both in intact and denuded oocytes only in the group incubated with TPA at 10 µM and the percent GVBD in intact and denuded oocytes were 41.43 ± 0.71 and 43.00 ± 2.50 respectively. Follicles cultured with 10 µM of TPA induced GVBD in appropriately 50% of both, intact and denuded oocytes. Around 50 % intact as well as denuded oocytes underwent GVBD after 18 hrs of incubation in the presence of 1µg/ml of progesterone in the culture media. However, by the end of culture period (48 hrs) both, TPA (10 µM) had induced 100% GVBD in intact and denuded oocytes.