The oocytic origin of dysgerminoma

An early dysgerminoma, found by chance in a grossly normal ovary, was completely blocked and multiply sectioned. It was found to have a mainly cortical location, being densest in the subtunical and adjacent zones where primordial follicles are normally most numerous, and to be associated with a reduction of the oocyte count in tumor-involved areas. An oocytic origin of the tumor is inferred from these findings and from other data, including the age incidence, available in the literature.