Urinary Bladder Calculi: Stones in the URINARY BLADDER; also known as vesical calculi, bladder stones, or cystoliths.Urinary Bladder: A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.Reference Books, Medical: Books in the field of medicine intended primarily for consultation.Calculi: An abnormal concretion occurring mostly in the urinary and biliary tracts, usually composed of mineral salts. Also called stones.History, Medieval: The period of history from the year 500 through 1450 of the common era.Urinary Bladder Neck Obstruction: Blocked urine flow through the bladder neck, the narrow internal urethral opening at the base of the URINARY BLADDER. Narrowing or strictures of the URETHRA can be congenital or acquired. It is often observed in males with enlarged PROSTATE glands.Urinary Calculi: Low-density crystals or stones in any part of the URINARY TRACT. Their chemical compositions often include CALCIUM OXALATE, magnesium ammonium phosphate (struvite), CYSTINE, or URIC ACID.Urinary Bladder Neoplasms: Tumors or cancer of the URINARY BLADDER.Urology: A surgical specialty concerned with the study, diagnosis, and treatment of diseases of the urinary tract in both sexes, and the genital tract in the male. Common urological problems include urinary obstruction, URINARY INCONTINENCE, infections, and UROGENITAL NEOPLASMS.Urologic Surgical Procedures: Surgery performed on the urinary tract or its parts in the male or female. For surgery of the male genitalia, UROLOGIC SURGICAL PROCEDURES, MALE is available.Ureteral Calculi: Stones in the URETER that are formed in the KIDNEY. They are rarely more than 5 mm in diameter for larger renal stones cannot enter ureters. They are often lodged at the ureteral narrowing and can cause excruciating renal colic.Mesophyll Cells: Large and highly vacuolated cells possessing many chloroplasts occuring in the interior cross-section of leaves, juxtaposed between the epidermal layers.Urinary Bladder Diseases: Pathological processes of the URINARY BLADDER.Dental Calculus: Abnormal concretion or calcified deposit that forms around the teeth or dental prostheses.Metabolic Diseases: Generic term for diseases caused by an abnormal metabolic process. It can be congenital due to inherited enzyme abnormality (METABOLISM, INBORN ERRORS) or acquired due to disease of an endocrine organ or failure of a metabolically important organ such as the liver. (Stedman, 26th ed)