Ovarian cancer. Coloured scanning electron micrograph (SEM) of bone tissue from a teratoma tumour of the ovary. Teratomas are malignant (cancerous) tumours that arise from the germ (sex) cells. Because germ cells are pluripotent, that is they can differentiate into any cell type, tumours contain a mixture of tissues. Bone, hair and teeth may form in the tumour. At centre is an osteoclast (blue), a type of bone cell that degrades and reabsorbs bone tissue. Magnification: x5000 when printed at 10 centimetres wide.