EXTERNAL DIGESTIVE SECRETIONS 



123 



extremity. These crypts are more numerous in the large intestine, 

 owing to the absence of villi (Fig. 42). 



The epithelium by which the crypts are lined is exactly 

 similar to that which clothes the surface of the villi. It consists 

 of irregular columnar cells, with a large nucleus, and striated 



FIG. 41 (Left). Section of intestinal mucous membrane (infant), shows three villi, with crypts of 

 Lieberkiihn. (Bohin and v. Davidoff. ) *. e, e, epithelium of villus ; c, connective tissue of 

 villus ; cc, goblet cells ; cr, Lieberkiihn's crypts ; cb, connective tissue at base of gland ; mm, 

 muscularis mucosae. 



FIG. 42 (Right). Section of mucous membrane of human colon, showing three crypts of Lieber- 

 kiihn. (Bohm and v. Davidoff.) z$ Q . e, epithelium; I, lumen ofigland; cc, goblet cells; ti, 

 interglandular tissue ; ta, areolar tissue of mucous membrane ; mm, muscularis mucosae. 



cuticular layer, and a somewhat flattened end which is attached 

 to the surface of the basement membrane, without extending 

 (as was formerly supposed) into the reticulated tissue of the villi. 

 Leucocytes are seen here and there between the epithelial cells 

 (Fig. 43). 



Goblet cells produced by mucoid degeneration of the ordinary 

 columnar cells are seen between the latter, the outer half of these 



