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The superficial layer of cells lining the alimentary canal and all its appendages, all glands and their ducts, blood vessels and lymphatics, serous cavities, etc. It often includes the epidermis (i. e., keratin-producing epithelial cells), and it is sometimes restricted to the alimentary canal, the glands and their appendages, -- the term endothelium being applied to the lining membrane of the blood vessels, lymphatics, and serous cavities.

The superficial layer of cells lining the alimentary canal and all its appendages, all glands and their ducts, blood vessels and lymphatics, serous cavities, etc. It often includes the epidermis (i. e., keratin-producing epithelial cells), and it is sometimes restricted to the alimentary canal, the glands and their appendages, -- the term endothelium being applied to the lining membrane of the blood vessels, lymphatics, and serous cavities.

One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.

Thin outer layer of skin.

Any cellular tissue covering a free surface or lining a tube or cavity.

The thin layer of epidermis, which covers parts deprived of derma, properly so called, -as the nipple, mucous membranes, lips, &c. Modern histological researches have shown that it exists, in different forms, pavement, cylinder, and vibratile or ciliated epithelium. Tesselated, pavement, scaly, lamellar, tubular, or flattened epithelium, Epithelium polyed'ricum, and E. lamellosum, (F.) Epithelium pavimenteux, covers the serous and synovial membranes, the lining of blood-vessels, and the mucous membranes, except where cylinder epithelium exists. It is spread over the mouth, pharynx and esophagus, conjunctiva, vagina, and entrance of the female urethra. Cylinder, Columnar or Prismatic epithelium, Epithelium cylitedricum, (F.) Epithelium cylindrigue is found in the intestinal canal, beyond the cardiac orifice of the stomach; in the larger ducts of the salivary glands; in the ductus communis choledochus, prostate, Cowper's glands, vesiculae seminales, vas deferens, tubuli uriniferi, and urethra of the male; and lines the urinary passages of the female, from the orifice of the urethra to the beginning of the tubuli uriniferi of the kidneys. In all these situations, it is continuous with tesselated epithelium, which lines the more delicate ducts of the various glands. For the uses of the ciliated epithelium, Epithelium vibrans, see Cilia. Mr. Bowman has applied the term spheroidal to a variety of epithelium, the cells of which, for the most part, retain their primitive roundness; or, being flattened where they touch, acquire a polyhedral figure. At times, these show a disposition to pass into the columnar, or the tesse­lated variety; and, hence, this form has been called the transitional. The spheroidal epithelium is found in the urinary passages, where it succeeds the columnar epithelium of the urethra at the internal orifice of that canal, and lines the whole of the bladder, ureters and pelves of the kidneys. It is found, also, in the excretory ducts of the mammary, perspiratory, and of many mucous, glands; and a modification of it lines the inmost secreting cavities or commencing ducts of glands generally.

Cellular substance of the skin and mucous membrane.

A membrane covering free surfaces of the body or lining cavities that communicate with the surface. It is composed of cells joined at their edges and forming one or more composite layers.