DEPARTMENT OF EMBRYOLOGY. 99 



of the gastric lymphatics develop, whose distribution was completely 

 worked out by Dr. Cash. The glands which are formed at the pyloro- 

 duodenal junction are unique. These glands prevent the injections of 

 the duodenal lymphatics from points on the stomach, which fact may 

 account for the failure to recognize a connection between the gastric 

 and duodenal lymphatics. 



The left gastric (splenic) trunk, which is somewhat smaller than the 

 right, divides into two branches, one going directly to the cardiac 

 pouch, the other passing to the hilum of the spleen. The latter branch 

 apparently does not enter the spleen, but traverses the splenic ligament 

 to the center of the greater curvature, where it ramifies over the an- 

 terior and posterior walls, anastomosing with vessels from the lesser 

 curvature, thereby establishing connections with the lymphatics of 

 the esophagus and the duodenum. No trace of an injection mass has 

 ever been found in sections taken at the hilum of the spleen, and it is 

 therefore to be inferred ihni these vessels are in no way related to the 

 spleen, but merely use its folds of peritoneiun to reach the stomach. 



Growth of these lymphatics is very rapid. As early as 20 to 40 mm. 

 the plexus is extremely dense and several layers in thickness; by 100 

 mm. the submucosa is completely filled by it. The vessels diminish in 

 size as they near the pylorus and appear to end blindly, although a few 

 of them anastomose wdth those of the deep plexus of the duodenum. It 

 is of interest to note tliat the vessels of the esophagus are derived from 

 two sources. Those of the lower end arise from the vessels of the 

 periesophageal ring; these meet and anastomose with others which 

 reach the esophagus from the bronchial plexus at the hilum of the lungs, 

 arising primarily from the thoracic duct. Thus drainage from the 

 esophagus takes place in two directions. 



The observations made on embryos were confirmed by injections 

 made of the stomach of adult animals. By injecting directly into the 

 submucosa at different points, the various pathways of drainage could 

 be readily seen by the spread of the mass through the vessels and its 

 appearance in the adjacent nodes. The three points of invasion from 

 the lesser curvature correspond to the chain of glands along the ascend- 

 ing and descending branches of the coronaiy and hepatic arteries. 

 The homogeneit}^ of the vessels, the richness of the plexuses, and the 

 number of connections preclude the theory of any sharply defined areas 

 by which drainage from the stomach may take place in a constant given 

 direction. There are four general pathways: (1) lesser curvature, 

 (2) greater curvature, (3) duodenum, and (4) esophagus. 



In studying the fate of the primary lymph sacs and the develop- 

 ment of lymph channels in the abdominal and pelvic regions, Dr. 

 Reichert succeeded in tracing all lymphatics of these regions to three 

 primary lymph sacs: the retroperitoneal sac, which arises ventral to 

 the aorta, and the paired iliac sacs, which arise dorso-lateral to the 



