THE DIGKSTIVE SYSTEM 



275 



Thcv pass over into much larger capillaries which form a dense 

 network just beneath the surface ci)ilheliuni. From the capillaries 

 small veins take origin which pierce the muscularis mucosae and form 

 a close-meshed venous plexus in the submucosa (Fig. 176). These in 

 turn give rise to larger veins, which accompany the arteries into the 

 mesentery. 



In the small intestine the distribution of the blood-vessels is 

 modified by the presence of the villi (Fig. 178). Each villus receives 

 one small artery, or, in the case of the larger villi, two or three small 

 arteries. The artery passes through the long axis of the villus close 

 under the epithelium to its summit, giving off a network of fine capil- 

 laries, which for the most part lie just beneath the epithelium. 

 From these, one or two small veins arise 

 which lie on the opposite side of the 

 villus from the artery. 



Lymphatics of the Stomach and 

 Intestine 



Small lymph or chyle capillaries 

 begin as blind canals in the stroma of 

 the mucous membrane among the tubular 

 glands (Fig. 176). In the small intestine 

 a lymph (chyle) capillary occupies the 

 centre of the long axis of each villus, 

 ending in a blind extremity beneath the 

 epithelium of its summit (Fig. 178). 

 These vessels unite to form a narrow- 

 meshed plexus of lymph capillaries in the 

 deeper part of the stroma, lying parallel 

 to the muscularis mucosae. Vessels from 

 this plexus pass through the muscularis 

 mucosas and form a wider meshed plexus 

 of larger lymph vessels in the submucosa. 

 A third lymphatic plexus lies in the con- 



FiG. 177. — Diagram of wall 

 of Stomach to show General Dis- 

 position of Lymphatics a, Term- 

 inal lymph channel in tissues 

 separating glands; b, superficial 

 lymphatic plexus in connective 

 tissue surrounding bases of 

 glands; c, submucous lymphatic 

 plexus; d, intermuscular lym- 

 phatic plexus; e, subperitoneal 

 lymphatic plexus. (Cuneo.) 



nective tissue which separates the two 

 layers of muscle. From the plexus in the submucosa, branches pass 

 through the inner muscular layer, receive vessels from the intermus- 

 cular plexus, and then pierce the outer muscular layer to pass into 

 the mesentery in company with the arteries and veins. 



