The ovarian surface epithelium (OSE) is the part of the pelvic mesothelium that covers the ovary. It comprises only a minute fraction of the ovary-however, it is the source of the epithelial ovarian carcinomas which are the prime cause of death from gynecological malignancies in North American and European women. The implication that OSE is the source of the epithelial ovarian cancers is based mainly on the demonstration of histopathological changes (1 ). The early stages of epithelial ovarian car-cinogenesis are poorly understood because these carcinomas are usually diagnosed in late stages and there are no adequate animal models for their study.