I/O 

 such 



FIG. 208. 



NORMAL HISTOLOGY. 



times the contents of the lacteals appear milky, in consequence 



of the emulsion formed by the ab- 

 sorbed oil ; during the intervals of 

 digestive inactivity the lacteal con- 

 tains the clear, straw-colored fluid 

 usually found within lymphatic ves- 

 sels. The villi disappear abruptly 

 at the ileo-caecal valve and are not 

 present in the large intestine. 



Among the structures of the in- 

 testinal wall usually included as 

 ' ' glands' ' two distinct groups must 



FIG. 209. 



Longitudinal section of villus from 

 intestine of dog, highly magnified : a, 

 columnar epithelium containing goblet- 

 cells (b) and migratory leucocytes (k) ; 

 c, basement membrane ; d, plate-like 

 connective-tissue elements of core ; e, e, 

 blood-vessels; _/", absorbent radicle or 

 lacteal. 



Transverse section of villus from intestine of dog ; 

 a, a, blood-vessels ; b, lacteal. 



be recognized the true and the false glands, the latter being simple 

 or compound lymph-follicles. These structures therefore fall under 

 the appropriate headings : 



Intestinal True-Glands. 



Glands of Lieberkuhn. 

 Glands of Brunner. 



Intestinal Lymph-Follicles. 



Solitary glands. 

 Agminated glands. 



The follicles, crypts, or glands of Lieberkuhn are very nu- 

 merous, forming an almost continuous layer of simple tubular de- 

 pressions throughout the intestines, large as well as small. They 

 occupy nearly the whole depth of the mucosa, their wavy extremities 

 approaching the muscularis mucosae. The columnar epithelium of 

 the free surface passes directly into the tubules to become the spherical 

 secreting cells, many of which undergo mucoid distention and 



