Figure 3

The induction of meiosis by progesterone compared to its induction by the products of phosphatidylethanolamine N-methylation. Denuded R. pipiens oocytes were transferred to Ringer's solution containing progesterone, PME, PDE and PC and incubated at 20-22°C. These phospholipids, when sonicated in Ringer's solution, formed clear solutions that were stable for several hours at room temperature. Denuded oocytes incubated in the phospholipid-Ringer's micelles for 6 h were rinsed, and then transferred to Ringer's solution for 6 h and nuclear membrane breakdown measured as described in methods. Sibling oocytes were preincubated in an N-methylation inhibitor [2-Methyl(amino)ethane (2-MAE)] for 1 h and transferred to Ringer's solution containing 2-MAE and progesterone or PME. Phospholipids were suspended in Ringer's solution as described in Methods. Results are expressed as means ± SEM for oocyte preparations from 3 females.