CILIATED CELLS 



TESTIS OF THE RABBIT. 



a, epithelium ; 6, connective tissue, 

 and eosin. x 550. 



Hematein 



The attached extremity of the columnar epithelial cells fre- 

 quently presents a longitudinally striated appearance. Such 

 " rodded epithelium "is 



specially characteristic of +** * * ^ O^ ^ 



the ducts of the salivary * JE^' *^* 

 glands and pancreas, and '"^ * 



of certain of the urinifer- J" * # 



ous tubules of the kidney. 



Short Columnar cells, FlG - 21. CUBOIDAL EPITHELIUM FROM THE BETE 



those whose three axes 



are approximately equal, 



are frequently described 



as cubical or cuboidal epithelium, but these cells do not differ 



either in structure or in distribution from the ordinary columnar 



type. 



CILIATED CELLS, Many cells carry upon their free surface 

 a group of delicate hair-like processes called cilia, or a single 

 flagellum, which during life are capable of a rapid vibratory or 



undulating motion. The direc- 

 tion of this ciliary motion is con- 

 stant, and is such as to produce 

 a definite current within the 

 fluids which bathe the surface of 

 these cells, whose direction is in- 

 variably from within outward 

 v * z *> toward the external surface 

 of the body. In the human body 

 cilia occur almost exclusively 

 upon the free extremities of 

 columnar-shaped cells. In some 

 of the lower animals, as, for ex- 

 ample, in the mouth of the frog, 

 cilia are also found upon poly- 

 hedral or pear-shaped cells. The 

 cilia are evidently extensions of 



the cytoplasm of the cell body, and may be regarded as modifica- 

 tions of its exoplasm. 



The ciliated cell border is differentiated from the protoplasm 

 of the cell body by a fine chromatic line which is divisible into a 

 number of knob-like segments. The cytoplasm and nucleus of 

 ciliated epithelium, except for the peculiarities dependent upon 



FIG. 22. COLUMNAR CILIATED EPITHE- 

 LIUM FROM THE EPIDIDYMIS OF A 

 RABBIT. 



a, epithelium; 6, connective tissue; 

 c, cilia. A leucocyte is seen between the 

 bases of the columnar cells. Hematein 

 and eosin. x 550. 



