Benign ovarian cyst. Light micrograph of a section through an ovary showing a cystadenoma. This cyst is an ingrowth on the ovary surface, the capsule tissue that normally surrounds the ovary is seen at right (light blue). As an adenoma it consists of epithelial cells derived from glandular ovarian tissue. These epithelial cells, arranged in glands with locules (cavities) stain a dark purple. This is because of their increased nuclear/cytoplasm ratio due to increased cell division. The cavities of the glands may fill with mucous produced by the epithelial cells. Cystadenoma can impair repro- ductive function of the ovary, and may become cancerous. Magnification: x20 at 6x7cm size.