Epithelium is an anatomical term for a basic type of bodily tissue. It comprises the external surface of the skin, the internal surfaces of the digestive, respiratory and urogenital systems, the closed serous cavities, the inner coats of the vessels, the acini and ducts of the secreting and excreting glands, the ventricles of the brain and the central canal of the spinal cord. The constituent cells of an epithelium are always closely packed together and the intercellular substance is reduced to a minimum. The cells comprising an epithelium are arranged in one (simple epithelium) or more (stratified epithelium and transitional epithelium) layers, usually supported on a basementmembrane and united together by a cement-like substance which is chemically similar to the matrix or ground-substance of the connective tissues.
The epithelium serves various purposes. The epithelium of the skin (known as the epidermis) serves primarily to protect the underlying tissue (the true skin, nerves and vessels which it contains). Th epithelium of the salivary glands, the pancreas, the gastric glands and the glands of the small intestine are comprised of cells which prepare the digestive juices. The cells comprising the epithelium of the intestinal villi are concerned with the absorption of the products of digestion. The cells of the epitheliums of the serous cavities provide a smooth, moist surface. Rather unusually in the body, the epithelium is devoid of a blood supply Research Epithelium
Abbreviations
Medicine
Research Epithelium