SQUAMOUS, STRATIFIED AND TRANSTIONAL EPITHELIUM. 41 



FLAT CELLS. 



If a cell be subjected to pressure on two opposite sides, a flattening 

 ensues, and a scale-like element results. Flat cells are united to form 

 a continuous structure in different ways. 



SQUAMOUS, STRATIFIED, AND TRANSITIONAL EPITHELIUM. 



The simplest method of tissue production by means of flat cells is 

 that of superposition, constituting squamous epithelium. Cells are 

 placed one over the other, generally without great regularity. If 

 regular, and in several layers, the structure is called stratified epithe- 

 lium ; if only in a few layers, it is termed transitional epithelium. 

 The superficial layer of the skin aifords an example of squamous,. 



FIG. 25. SQUAMOUS CELLS FROM BUCCAL EPITHELIUM. 

 A. Typical cell. B. Its nucleus. 



C. Union by overlapping forming laminae. 



D. Salivary corpuscles. X 400. 



stratified epithelium. The bladder, pelvis of the kidney, and vagina 

 are lined with transitional epithelium. 



The thin, flat scales from the mouth may be demonstrated by 

 scraping a drop of saliva from the tongue with the handle of a 

 scalpel, transferring it to the slide, and applying the cover. The 

 size of the drop of saliva should be carefully adjusted so as to fill the 

 space between the cover-glass and slide. Too little will cause the 

 cover to adhere so tightly to the slide as to press the cells out of 

 form; too much, and the saliva flows over the cover and soils the ob- 

 jective. With a glass rod, place a drop of the dilute eosin solution 



