STRATIFIED EPITHELIUM 27 



Stratified Epithelium. The term stratified epithelium is employed 

 to describe the type found in the skin or its derivatives in which the cells 

 forming the epithelium are arranged in a considerable number of superim- 

 posed layers. The shape and size of the cells of the different layers, as well 

 as the number of layers, vary in different situations. Thus the superficial cells 

 may be either squamous or columnar in shape and the deeper cells range 

 from polygonal to columnar in form. 



Stratified Squamous. The intermediate cells are polygonal in shape and 

 approach more to the flat variety the nearer they are to the surface, and to the 



FIG. 26. Squamous Epithelium Scales from the Inside of the Mouth. X 260. (Henle.) 



columnar as they approach the lowest layer. In many of the deeper layers 

 of epithelium in the mouth and skin, the outline of the cells is very irregular, 

 in consequence of processes passing from cell to cell across these intervals. 

 Such cells, figure 28, are termed " prickle " cells. These " prickles " are the in- 

 tercellular bridges which run across from cell to cell, the interstices being filled 

 by the transparent intercellular lymph. When this increases in quantity 



FIG. 27. Vertical Section of the Stratified Epithelium Covering the Front of the Cornea. Highly 

 magnified. (Schafer.) c, Lowermost columnar cells; p, polygonal cells above these; ft, flat- 

 tened cells near the surface. The intercellular channels, bridged by minute cell processes, are 

 well seen. 



in inflammation the cells are pushed further apart, and the connecting fibrils 

 or " prickles" are elongated and more clearly visible. 



The columnar cells of the deepest layer are distinctly nucleated; they 

 multiply rapidly by division; and as new cells are formed beneath, they press 

 the older cells forward, to be in turn pressed forward themselves toward the sur- 

 face, gradually altering in shape and chemical composition until they die and 

 are cast off from the surface. 



