n :  a membrane rich in mucous glands : specif  :  one that lines body passages and cavities which communicate directly or indirectly with the exterior (as the alimentary, respiratory, and genitourinary tracts), that functions in protection, support, nutrient absorption, and secretion of mucus, enzymes, and salts, and that consists of a deep vascular connective-tissue stroma which in many parts of the alimentary canal contains a thin but definite layer of nonstriated muscle and a superficial epithelium which has an underlying basement membrane and varies in kind and thickness but is always soft and smooth and kept lubricated by the secretions of the cells and numerous glands embedded in the membrane - called also mucosa  - compare SEROUS MEMBRANE  .
 
 
 
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