[Ultrastructure of malignant Brenner tumor]

Electron microscopic study of five malignant Brenner tumors showed that the histologic features resembled nonkeratinized squamous carcinoma of uterine cervix. Intracytoplasmic glands and cysts, abundant glycogen, numerous desmosome, cilia and desmosome-tonofilament complex were the ultrastructural features of malignant Brenner tumor. Among them, cilium is characteristic for ovarian surface epithelium and Mullerian epithelium, rather than for uro-epithelium. The desmosome-tonofilament complex is the specific structure for squamous cell, also not for uro-epithelium. So the appearance of cilium in malignant Brenner tumor indicates that the tumor is derived from Mullerian epithelium, and the presence of desmosome-tonofilament complex evidences that the tumor cells possess the characteristics of squamous cells. This study further proves that malignant Brenner tumor arises from Mullerian epithelium.