COLUMNAR EPITHELIUM. 



199 



or cylinder-epithelium, in which the cells have a prismatic figure, and are set upright 

 on the surface which they cover. In profile a row of these cells looks for the 

 most part like a close palisade (fig. 231) ; but viewed from the surface each cell has 

 a polygonal outline, the cells being flattened where they touch, from mutual corn- 



Fig. 230. COLUMNAR EPITHELIUM CELLS OF THE RABBIT'S INTESTINE. (E. A. S.) 



The cells have been isolated after maceration in very weak chi'omic acid. The protoplasm is reticular 

 and vacuolated ; the striated border (sir. ) is well seen, and the bright disc separating this from the cell- 

 protoplasm ; n, nucleus with intranuclear network ; a, a thinned out wing-like projection of the cell 

 which probably fitted between two adjacent cells. 



Fig. 231. A ROW OF COLUMNAR CELLS FROM AN INTESTINAL VILLUS OF THE RABBIT. (E. A. S. ) 



sir, striated border ; w, wander-cells between the epithelium cells. 



pression, so that thus again a mosaic pattern is produced. Columnar epithelium- 

 cells vary much in form, in dimensions, and even in structure. Those which may 

 be looked upon as typical are of a long tapering figure, the finer extremity being set 



Fig. 232. CROSS-SECTION OF A VILLUS OF THE INTESTINE. (E. A. S.) 



e, columnar epithelium with striated border ; g, goblet cell, with its mucus partly extended ; I, 

 lymph-corpuscles between the epithelium-cells ; b, basement membrane ; c, sections of blood capillaries ; 

 m, section of plain muscular fibres ; c. I. , central lacteal. 



Fig. 233. GOBLET-CELL FROM TRACHEA. HIGHLY MAGNIFIED. (Klein.) 



upon a surface, and the other and larger end being free. At their sides and edges 

 the columnar cells are often irregular and jagged, especially where, as is often the 

 case, lymphoid or wander-cells are met with between the epithelium-cells 

 (fig. 231, w). Indeed the cells are not by any means so regular in shape as they are 

 often figured, being often compressed laterally, and sometimes extended sideways 

 into flattened lamellae (fig. 230, a), which fit between the adjacent cells of the epithe- 



