398 



MANUAL OF HISTOLOGY. 



been called, to be the artificially altered cement-substance al- 

 ways present between such adjacent cells. Ikunner's glands 

 abound only in the duodenum, but a few may occasionally be 

 seen lower down the intestine. Their ducts, after traversing 

 the muscularis mucosse, ascend almost vertically between the 

 crypts, opening on the free surface of the mucous membrane. 



Fig. 171. Crypts and interfollicnlar connective tissue, from the intestine of the rabbit : K, crypt ; 

 a. n, epithelium ; <J, adenoid tissue, from which the cells have becfti removed by pencilling ; 'I', fibrous 

 tifume on the opposite side. Verson. 



These crypts represent open spaces within the so-called 

 follicles of Lieberkukn, which are tubular glands placed verti- 

 cally in the intestinal mucous membrane, existing throughout 

 its entire extent. 



They -form a continuous layer, except where the upward 

 projection of a lymph-follicle creates an interruption. These 

 glands open at the base of the villi, the epithelial covering of 

 the latter being continued down into the tubular depressions 

 which they constitute in the mucous membrane. The cells of 

 this stratum naturally appear broader at their attached than at 



