Mast cells. Most histamine in the body is generated in granules in mast cells and in white blood cells called basophils and eosinophils. Mast cells are especially numerous at sites of potential injury â the nose, mouth, and feet, internal body surfaces, and blood vessels.
urban adjective. âº of or in a âcity or âtown: Many âAmericans were âleaving the âfarm for the âpromise of urban âlife. Over 82% of Texans âlive in urban âareas. (Definition of urban from the Cambridge Academic Content Dictionary Â© Cambridge University Press).
The United States Census Bureau recognizes only urban and rural areas, and assigns specific population requirements to them for classification purposes. An urban area is an area in which the population is greater than 50,000 people, or an area in which the population is between 2,500 and 50,000. A rural area is defined as an area of less than 2,500 people. Suburbs, however, are geographically defined as pockets of populations in the outlying areas of large urban centers.