74 



THE TISSUES 



Simple Epithelium 



In simple epithelium the cells are arranged in a single layer, 

 (a) Simple squamous epithelium consists of flat scale-like cells 

 which are united by an extremely small amount of intercellular sub- 



FiG. i6.— From Section of Cat's Lung, stained with silver nitrate, showing out- 

 lines of the Simple Squamous Epithelium Lining the Air Vesicle, a, Two epithelial 

 cells; b, the wavy stained intercellular substance; c, foetal cells; d, connective tissue. 



stance. The edges of the cells are smooth or serrated. Seen on 

 flat, they present the appearance of a mosaic. Seen on edge, the 

 cells appear fusiform, being thickest at the center, where the nucleus 









, # 



— d 







Fig. 17. — Simple Columnar Epithelium from the Human Small Intestine, a, 

 Mucous (goblet) cell; b, basement membrane; c, thickened free border (cuticula); 

 d, leucocyte among the epithchal cells; e, replacing ceil. 



is situated, and thinning out toward the periphery. Simple squa- 

 mous epithelium has but a limited distribution in man. It occurs 

 in the lungs as non-nucleated respiratory epithelium, in Bowman's 



i 



