Female transgenic mice expressing the transforming region of simian virus 40 (SV40) under control of the Mullerian inhibitory substance type II receptor (MISIIR) gene promoter develop bilateral ovarian tumors. Histologically, these tumors are poorly differentiated carcinomas with occasional cysts and papillary structures present at the surface of the ovary. These tumors disseminate intraperitoneally, invade omentum and form ascites as do human ovarian carcinomas. The cover features a ScanScope overview image of a representative H&E section of the ovary substituted by tumor cells. For details, see the article by Connolly et al. on page 1389 of this issue.