LYMPHATICS IN THE STOMACH OP THE EMBRYO PIG. 9 



The origin of the ascending duodenal group is somewhat varied in the different 

 specimens. In some, these vessels spring from the right gastric trunk as it leaves 

 the retroperitoneal sac; in others, they arise from the sac itself just posterior to the 

 right gastric trunk. In their course through the duodenal mesentery they present 

 no unusual features, but the lymph-glands, later formed along their course at the 

 pyloro-duodenal junction, offer a striking point of difference from the glands of the 

 other vessels leaving the stomach. These glands prevent the injection of the 

 duodenal lymphatics from points on the stomach and this fact most likely accounts 

 for the failure to recognize such a connection between gastric and duodenal lym- 

 phatics by methods such as have been hitherto employed to demonstrate them. 



The left gastric trunk, arising from the retroperitoneal sac, immediately 

 divides into two branches. The lesser branch passes by way of the extreme left 

 portion of the omental bursa to the anterior surface of the stomach at the base of 

 the cardiac pouch. The cardiac pouch is a transient, embryonic structure. In the 

 pig, during embryonic life, there is a slight annular constriction of the stomach wall 

 near the cardiac end, which gives to that portion of the stomach a pouch-like 

 appearance (fig. 5). This structure becomes less evident as development proceeds 

 and in very late stages is scarcely perceptible. The lesser branch of the left cardiac 

 trunk is the principal source of invasion of the pouch and forms rich anastomoses 

 with the vessels reaching the stomach at the center of the lesser curvature and 

 esophageal opening. The greater branch of the left gastric trunk enters the omental 

 bursa just medial to the lesser branch. It passes by way of the posterior wall of the 

 omental bursa (which in this region constitutes the splenic ligament) to the hilum of 

 the spleen; from this point these vessels pass by way of the gastro-splenic ligament 

 to the center of the greater curvature of the stomach (figs. 4 and 5). The number 

 of vessels comprising this set varies from two to four. It is always difficult to be 

 certain of the exact number, as they are situated very close together in a densely 

 entwined mass. They have never been observed to enter the spleen, and sections 

 taken through the point where they pass the hilum of that organ have consistently 

 failed to demonstrate a trace of injection mass within its interior. So it may be 

 said that these vessels appear in no way related to the spleen itself but merely take 

 advantage of its folds of peritoneum to make their way to the stomach. They 

 reach that organ on the greater curvature, at a point about midway between the 

 cardia and pylorus, and from this point their growth proceeds in opposite directions. 

 Approximately half of them pass to the right, along the greater curvature, to meet 

 the pyloric vessels from the duodenum which grow along this course ; the other half 

 pass along the greater curvature, to the left, where they meet anastomosing vessels 

 from the cardia, esophageal ring, and lesser curvature (fig. 4). All along their 

 course on the greater curvature these vessels give off branches at right angles to 

 themselves, which extend over the anterior and posterior walls of the stomach to 

 meet similar branches given off from the great mass of lymphatics of the lesser 

 curvature. 



Concomitant with the growth of the subserous trunks, growth of the other 

 plexuses takes place. Sprouting branches from the early trunks of the subserosa 



