86 



THE TISSUES. 



male urethra and the vas deferens, and in certain regions of the 

 larynx. 



The ciliated variety of this epithelium differs from the foregoing 

 in that the superficial columnar cells are provided with cilia. Strati- 

 fied ciliated columnar epithelium is found in the respiratory portion 



Fig. 46. Schematic dia- Fig. 47. Ciliated cells from the bronchus of the 



gram of stratified columnar epi- dog, the left cell with two nuclei ; X 600. 

 thelium. 



of the nose, larynx, trachea, and larger bronchi, in the Eustachian 

 tube, epididymis, and a portion of the vas deferens. 



All epithelial cells are probably joined together by short pro- 

 cesses forming intercellular bridges, the lymph supplying them with 

 nourishment circulating in the intercellular spaces thus formed. 

 Toward the surface, these intercellular spaces are roofed over, thus 

 preventing the escape of the fluid. When seen from the surface, 

 epithelia treated by certain methods (iron-hematoxylin) show the 

 cells joined together by very minute, clearly defined and continuous 



Goblet cell. 



Cilia. 



Fig. 48.- Cross-section of stratified ciliated columnar epithelium from the 

 trachea of a rabbit. 



cement-lines. Bonnet has called them terminal ledges or bars 

 (Schlussleisten). The function of this structure would seem to 

 consist in its power to prevent the escape of lymph from the sur- 

 face, and the penetration of micro-organisms (M. Heidenhain, 92 ; 

 Bonnet, 95). 



