Benign, borderline and malignant serous cystadenomas of the ovary. A transmission and scanning electron microscopical study.

In this study benign, malignant and borderline types of ovarian cystadenomas were studied by different morphological, transmission electron microscopical and scanning electron microscopical methods. The main cell type, the tubal cell, contained numerous microvilli projecting into the lumen, some cells also possessed cilia in addition to microvilli. Infrequently endometrial like cells were found with branched cilia intermixed with microvillous projections similar to that of the endometrium. Endocervical-like cells, very uncommon, evidenced numerous cytoplasmic projections extending into the lumen, arranged in a wavelike pattern. The surface structures were well developed in benign tumors, in borderline tumors focal denuded areas with histologically atypias were seen and in malignant ones the surface cells were devoid of specialised structures. The results also support a metaplastic origin from ovarian surface epithelium for these tumors.