46 



TISSUES 



These different shaped glands are lined by epithelial 

 cells, depending on the situation and function. Their 

 secretions are liquid, and may be serous, mucous, or 

 mixed, which the lining cells secrete as needed by the 

 organ to perform its physiologic function. 



FIG. 22 



Tubular glands. 



Alveolar glands. 



Diagram of various forms of glands; a, duct; x, simple tubule; xx, simple 

 alveolus. (After Szymonowicz.) 



Serous Membranes. They are membranes covered 

 by a single layer of flattened cells, with a large pro- 

 jecting nucleus; these cells are held together by a 

 intercellular cement. They are termed endothelial 

 cells. Serous membranes never have a basement 

 membrane and line cavities that do not communicate 

 with the air. These membranes appear smooth, 



