Ovarian cancer blood vessel. Coloured scanning electron micrograph (SEM) of a section through a small blood vessel in a cancer of the ovary. Red blood cells are seen in the central space (lumen). Cancer is uncontrolled cell replication, and the rapidly growing tumour requires extra blood supply for this growth. The presence of excessive amounts of blood vessels is one sign of cancer. Cancer of an ovary (which produces the female reproductive cells) does not normally produce symptoms until it is in an advanced stage. The prognosis is poor and surgical removal of the tumour is followed by use of chemotherapy. Magnification: x400 when printed 10cm wide.