CH. III.] 



CILIATED EPITHELIUM 



23 



various orifices of the body. It lines the upper end of the alimentary 

 canal from the mouth to the point where the oesophagus or gullet 

 enters the stomach. The deepest layers are columnar or cubical in 

 shape, and the surface layers are composed of flattened scales, their 



Fio. 32. 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 ; &, a portion of the 

 substance of cornea. (Klein.) 



protoplasm being replaced by horny material or keratin. Covering 

 the front of the cornea of the eye is a typical form of stratified 

 epithelium (fig. 32), but the number of layers is not so great as it is 

 in the majority of such epithelia. 



Ciliated Epithelium. 



The cells of ciliated epithelium are generally of columnar shape 

 (fig. 33), but they may occasionally be spheroidal (fig. 34). 



FIG. 33. Ciliated epithelium from the human 

 trachea, a, Large fully-formed cell ; 6, 

 shorter cell ; c, developing cells with more 

 than one nucleus. (Cadiat.) 



Fia. 34. Spheroidal ciliated 

 cells from the mouth of 

 the frog, x 800 diame- 

 ters. (Sharpey.) 



Each cell is surmounted by a bunch of fine tapering filaments. 

 They were originally called cilia because of their resemblance in shape 

 to eyelashes. They differ from eyelashes in being extremely small, 



