Light micrograph showing adenomyosis of the human uterus, a term used to describe the abnormal presence of islands of endometrial glands and stroma deep within the myometrium (the muscle that supports the endometrium, the glandular uterine lining). Here, normal myometrium is stained pink, with displaced (ectopic) glands appearing white. The large gland at centre is surrounded by a purple-staining area of stroma. Adenomyosis may result in the overall enlargement of the uterus or the local formation of a mass known as an adenomyoma. Ectopic endometrium responds to ovarian hormones, so its confinement by surrounding tissue may give rise to pain. UFIG. 16.10 BASIC HISTOPATHOLOGY