Endometrial Hyperplasia: Benign proliferation of the ENDOMETRIUM in the UTERUS. Endometrial hyperplasia is classified by its cytology and glandular tissue. There are simple, complex (adenomatous without atypia), and atypical hyperplasia representing also the ascending risk of becoming malignant.Endometrial Neoplasms: Tumors or cancer of ENDOMETRIUM, the mucous lining of the UTERUS. These neoplasms can be benign or malignant. Their classification and grading are based on the various cell types and the percent of undifferentiated cells.Hyperplasia: An increase in the number of cells in a tissue or organ without tumor formation. It differs from HYPERTROPHY, which is an increase in bulk without an increase in the number of cells.Endometrium: The mucous membrane lining of the uterine cavity that is hormonally responsive during the MENSTRUAL CYCLE and PREGNANCY. The endometrium undergoes cyclic changes that characterize MENSTRUATION. After successful FERTILIZATION, it serves to sustain the developing embryo.Progestins: Compounds that interact with PROGESTERONE RECEPTORS in target tissues to bring about the effects similar to those of PROGESTERONE. Primary actions of progestins, including natural and synthetic steroids, are on the UTERUS and the MAMMARY GLAND in preparation for and in maintenance of PREGNANCY.Uterine Diseases: Pathological processes involving any part of the UTERUS.Polyps: Discrete abnormal tissue masses that protrude into the lumen of the DIGESTIVE TRACT or the RESPIRATORY TRACT. Polyps can be spheroidal, hemispheroidal, or irregular mound-shaped structures attached to the MUCOUS MEMBRANE of the lumen wall either by a stalk, pedunculus, or by a broad base.Carcinoma, Endometrioid: An adenocarcinoma characterized by the presence of cells resembling the glandular cells of the ENDOMETRIUM. It is a common histological type of ovarian CARCINOMA and ENDOMETRIAL CARCINOMA. There is a high frequency of co-occurrence of this form of adenocarcinoma in both tissues.Levonorgestrel: A synthetic progestational hormone with actions similar to those of PROGESTERONE and about twice as potent as its racemic or (+-)-isomer (NORGESTREL). It is used for contraception, control of menstrual disorders, and treatment of endometriosis.Uterine Hemorrhage: Bleeding from blood vessels in the UTERUS, sometimes manifested as vaginal bleeding.Endometritis: Inflammation of the ENDOMETRIUM, usually caused by intrauterine infections. Endometritis is the most common cause of postpartum fever.Hysterectomy: Excision of the uterus.Intrauterine Devices, Medicated: Intrauterine devices that release contraceptive agents.Curettage: A scraping, usually of the interior of a cavity or tract, for removal of new growth or other abnormal tissue, or to obtain material for tissue diagnosis. It is performed with a curet (curette), a spoon-shaped instrument designed for that purpose. (From Stedman, 25th ed & Dorland, 27th ed)Uterine Neoplasms: Tumors or cancer of the UTERUS.Contraceptive Agents, Female: Chemical substances or agents with contraceptive activity in females. Use for female contraceptive agents in general or for which there is no specific heading.Dilatation and Curettage: Dilatation of the cervix uteri followed by a scraping of the endometrium with a curette.Lynestrenol: A synthetic progestational hormone used often in mixtures with estrogens as an oral contraceptive.Precancerous Conditions: Pathological processes that tend eventually to become malignant. (From Dorland, 27th ed)Animals, ZooProstatic Hyperplasia: Increase in constituent cells in the PROSTATE, leading to enlargement of the organ (hypertrophy) and adverse impact on the lower urinary tract function. This can be caused by increased rate of cell proliferation, reduced rate of cell death, or both.Uterus: The hollow thick-walled muscular organ in the female PELVIS. It consists of the fundus (the body) which is the site of EMBRYO IMPLANTATION and FETAL DEVELOPMENT. Beyond the isthmus at the perineal end of fundus, is CERVIX UTERI (the neck) opening into VAGINA. Beyond the isthmi at the upper abdominal end of fundus, are the FALLOPIAN TUBES.Adenocarcinoma: A malignant epithelial tumor with a glandular organization.Carcinoma in Situ: A lesion with cytological characteristics associated with invasive carcinoma but the tumor cells are confined to the epithelium of origin, without invasion of the basement membrane.Hysteroscopy: Endoscopic examination, therapy or surgery of the interior of the uterus.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Rats, Mutant Strains: Rats bearing mutant genes which are phenotypically expressed in the animals.World Health Organization: A specialized agency of the United Nations designed as a coordinating authority on international health work; its aim is to promote the attainment of the highest possible level of health by all peoples.Adrenal Hyperplasia, Congenital: A group of inherited disorders of the ADRENAL GLANDS, caused by enzyme defects in the synthesis of cortisol (HYDROCORTISONE) and/or ALDOSTERONE leading to accumulation of precursors for ANDROGENS. Depending on the hormone imbalance, congenital adrenal hyperplasia can be classified as salt-wasting, hypertensive, virilizing, or feminizing. Defects in STEROID 21-HYDROXYLASE; STEROID 11-BETA-HYDROXYLASE; STEROID 17-ALPHA-HYDROXYLASE; 3-beta-hydroxysteroid dehydrogenase (3-HYDROXYSTEROID DEHYDROGENASES); TESTOSTERONE 5-ALPHA-REDUCTASE; or steroidogenic acute regulatory protein; among others, underlie these disorders.Leiomyoma: A benign tumor derived from smooth muscle tissue, also known as a fibroid tumor. They rarely occur outside of the UTERUS and the GASTROINTESTINAL TRACT but can occur in the SKIN and SUBCUTANEOUS TISSUE, probably arising from the smooth muscle of small blood vessels in these tissues.