CH. III.] 



STRATIFIED EPITHELIUM. 



35 



The nucleus is often not apparent. The really cellular nature 

 of even the dry and shrivelled scales cast off from the surface of 

 the epidermis^ can be proved by 

 the application of caustic potash, 

 which rapidly causes them to 

 swell and assume their original 

 form. 



The squamous cells exist in 

 the greatest number of layers in 

 the epidermis or superficial part 

 of the skin ; the most superficial 

 of these are being continually 



removed by friction, and new cells from below supply the place 

 of those cast off. 



Fig. 47. Vertical section of the stratified epithelium of the rabbit's cornea, a, anterior 

 epithelium, showing the different shapes of the cells at various depths from the free 

 surface ; b, a portion of the substance of cornea. (Klein.) 



The intermediate cells approach more to the flat variety the 

 nearer they are to the surface, and to the columnar as they 

 approach the lowest layer. There 

 may be considerable intercellular 

 intervals ; and 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 in- 

 tervals. 



Such cells (fig. 48) are termed 

 " ridge and furrow," " cogged " 

 or " prickle " cells. These 

 "prickles" are prolongations of 

 the intracellular network which 

 run across from cell to cell, thus joining them together, the inter- 

 stices being filled by lymph and transparent intercellular cement 



Dl 



Fig. 48. Jagged cells from the middle 

 Uyere of stratified epithelium, from 

 a vertical section of the gum of a 

 new-bom infant. (Klein.) 



