32 



THE ESSENTIALS OF HISTOLOGY. 



Ciliated epithelium. The cells of a ciliated epithelium are also 

 usually columnar in shape (fig. 31), but in place of the striated border 

 the cell is surmounted by a bunch of fine tapering filaments which, 

 during life, move spontaneously to and fro, and serve to produce a 

 current of fluid over the surface which they cover. 



The cilia are to be regarded as active prolongations of the cell- 

 protoplasm. The border upon which they are set is bright, and 

 appears formed of little juxtaposed knobs, to each of which a cilium is 

 attached. In the large ciliated cells which line the alimentary canal 

 of some molluscs (fig. 32), the knob may be observed to be prolonged 

 into the protoplasm of the cell as a fine varicose filament, termed the 

 rootlet of the cilium. These filaments perhaps represent the longi- 



FIG. 30. GOBLET-CELL 

 FROM THE TRACHEA. 

 (Klein.) 



FIG. 31. COLUMNAR CILI- 

 ATED EPITHELIUM-CELLS 

 FROM THE LOWER PART 



OF THE NASAL PASSAGES. 

 EXAMINED FRESH IN 

 SERUM. (Sharpey.) 



FIG. 32. CILIATED CELL, 

 FROM THE INTESTINE 



OF A MOLLUSC. (Engel- 



mann.) 



tudinal striae often seen in the protoplasm of the columnar cell, the 

 bunch of cilia being homologous with the striated border. The proto- 

 plasm and nucleus have a similar vacuolated and reticular structure in 

 both kinds of cell. 



