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CHAPTEE XII 

 MUCOUS MEMBRANES SECRETING GLANDS 



THE histologic structures which are necessary for the forma- 

 tion of a secretion include an epithelial surface, and a tunica pro- 

 pria of connective tissue which supports the requisite blood and 

 lymphatic vessels and the controlling nerve supply. These struc- 

 tures may either form smooth membranous surfaces or apparent 

 epithelial invaginations. The former are found on the surface of 

 the mucous membranes, the latter are the secreting glands. 



MUCOUS MEMBRANES, The mucous membranes may be said 

 to include all those secreting surfaces which are directly or indi- 

 rectly connected with the surface of the body, hence their epithe- 

 lial clothing is continuous with that of the skin. The mucous 

 membranes form the lining coat of the respiratory and alimentary 

 systems, together with the ducts of their secreting glands : in the 

 nose this membrane is continuous through the tear ducts with the 

 conjunctiva of the eye and through the Eustachian tubes with the 

 lining membrane of the middle ear. The broad expanse thus 

 formed is known as the gastro-pneumonic mucous membrane. A 

 second membranous sheet, the genito-urinary mucous membrane, 

 clothes the organs of the genital and urinary systems : it thus 

 forms the lining membrane of the vagina, uterus, and Fallopian 

 tubes, of the urethra, bladder, and pelvis of the kidney, of the 

 ducts and tubules of the prostate gland, the testis, and the smaller 

 secreting glands which are connected with the genital system. 



A mucous membrane consists of a superficial layer of epithe- 

 lium of varying type, which rests upon a basement membrane 

 (membrana propria) and is in turn supported by an investment of 

 connective tissue, the tunica propria, or corium. The tunica pro- 

 pria is richly supplied with small blood vessels and lymphatics ; its 

 nerve fibrils are not only distributed to the walls of the blood 

 vessels but in many cases send terminal filaments which enter the 

 epithelial layer and terminate in contact with the secreting cells. 

 The mucous membranes are mostly contained within hollow organs 

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