COLUMNAR EPITHELIUM. 



31 



cubical shape, and occurs in the tubules of the testis and in the 

 alveoli of the thyroid gland. 



V 



FIG. 18. Isolated cells of squamous epithelium (surface cells of the stratified 

 squamous epithelium lining the mouth) : a, a, cells presenting under surface ; 

 b, cell with two nuclei (Huber). 



Columnar Epithelium (Fig. 20). Columnar epithelium is 

 sometimes described as cylindric epithelium. The cells are of a 

 prismatic shape, and usually rest upon 

 a basement-membrane. When looked 

 at from the free end, they present the 

 appearance of a mosaic ; when ob- 

 served from the side, the free edge 

 is seen to be striated. 



This variety of epithelium lines 

 the stomach and intestines, and the 

 glands which open into these cavi- 

 ties. It covers the mucous mem- 

 hrane of most of the urethra, the vas 

 deferens, prostate, Cowpers glands, f r0 g; x400(Bdhmand Davidoff). 

 and the ducts of most glands. The 

 germinal epithelium which covers the ovary is of this type. 



Goblet-cell (Fig. 22). A peculiar modification of columnar 



Goblet-cell. 

 Cuticular border. 



FIG 20 Simple columnar epithelium from the small intestine of man : a, isolated 

 cells ; 6, surface view ; c, longitudinal section (Huber). 



