180 



THE ESSENTIALS OF HISTOLOGY. 



the fact that along the caecum and colon the longitudinal muscular 

 fibres are gathered up into three thickened bands which produce 

 puckerings in the wall of the gut. 



The mucous membrane of the large intestine is beset with simple 

 tubular glands somewhat resembling the crypts of Lieberkiihn of the 

 small intestine, and lined by columnar epithelium similar to that of the 

 inner surface of the gut, but containing many more mucus-secreting or 

 goblet cells (fig. 212). The extremity of each gland is usually slightly 

 dilated. The interglandular tissue is like that of the stomach, as is 



FlG. 212. A GLAND OF THE LARGE 

 INTESTINE OF THE DOG. (From 



Heidenhain and Klose.) 



b, in longitudinal ; c, in transverse 

 section. 



also the arrangement of the blood-vessels and lymphatics in it. The 

 nerves of the large intestine also resemble those of the small intestine 

 and stomach in their arrangement. 



At the lower end of the rectum the circular muscular fibres of the 

 gut become thickened a little above the anus so as to form the internal 

 sphincter muscle. In this region also there are a number of compound 

 racemose mucous glands opening on to the surface of the mucous 

 membrane (anal glands}. 



