50 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



cell rests upon a basement membrane that is usually 

 considered to be made up of basal processes of the 

 basal cells. 



The free surfaces of epithelial cells may develop 

 cilia, which serve the purpose of sweeping away 

 fluids or foreign bodies. In many instances a deli- 

 cate lining called the cuticle covers the free ends. 

 The cuticle is to be regarded as a cell product, and 

 since in many cases a fine transverse striation can 

 be seen, it seems probable that the cuticle is built 

 from a large number of transverse rods cemented 



Fig. 15. Epithelial cells from skin of frog. Surface view of external layer. 



together. In columnar cells the nucleus is usually 

 found at the basal end, thus being placed nearer the 

 blood and lymph supply, the nourishing cell media. 



Epithelial tissue is classified as: (i) simple or 

 (2) stratified. 



i. Simple epithelium, consisting of a single layer 

 of cells. 



(a) Simple squamous, flat single layer of cells, 

 found in the alveoli of the lung and in Bowman's 

 capsule of the kidney. 



