Light micrograph of human ovarian cystadenoma. This tumour of the ovary grows as a large mass and often virtually replaces the normal structure. The entire field of this picture with the exception of blood vessels (bright red band, bottom) consists of multioculated cysts. Each is lined by columnar cells, stained purple next to the surface of the cystic locule, and pale blue towards its centre. The cystic spaces at the centre of each locule contain a thick mucoid material, seen here as pale blue masses, shrunken within the (white) lumen of the space. Cystadenoma is the name given to benign neoplastic cysts. Magnification x20 at 35mm size.