PATTERNS OF THE A-V PATHWAYS 



905 



fig. 9. Types of antimesenteric 

 anastomoses. [From Noer (90).] 



(the mural trunks). In his search for an experimental 

 animal which might have a vascular distribution 

 similar to man, he observed 14 different animals. The 

 basic architecture was found to be similar in all 

 animals in that the intestinal arteries formed mesen- 

 teric arcades or arches which in turn gave rise to vasa 

 recta, which then proceeded to the intestinal wall to 

 form mural trunks. Striking variations in the numbers 

 of mesenteric arcades were found among the species 

 as well as differences in the pattern of the vasa recta, 

 including their length and whether or not they had 

 anastomotic connections with one another. The mural 

 trunks in the human stomach were found to ramify in 

 two ways, a similar arrangement being seen in other 

 animals. A single vessel passing to the antimesenteric 

 area might give off lateral branches along the way, 

 or the vessel might break up into several branches 

 rather quickly and subdivide in an arboreal fashion. 

 Three types of anastomoses between the mural trunks 

 in the antimesenteric area were found to be /) direct 

 communication between the mural trunks of the two 

 sides, 2) a plexiform arrangement, 3) short vessels 

 joining arcuate mural anastomoses (fig. 9). Veins 

 were found to follow the arteries with few exceptions. 



Although Noer was not the first to describe the 

 arcuate patterns found in the arterial and venous 

 vessels of the intestine, his report is extensive and de- 

 tailed, and contains a comprehensive review of the 

 literature up to that time. 



Investigations of the alimentary tract during the 

 next few years centered around the absence or 

 presence of arteriovenous anastomoses, especially in 

 the human stomach. Barclay & Bentley(7), stimulated 

 by the findings of Trueta et al. ( 1 20) of vascular shunts 

 in the kidney, proposed that in the wall of the stomach 

 there were arteriovenous anastomoses in the region of 

 the submucous plexus, and that when these arterio- 

 venous anastomoses were open, active circulation 

 through the vessels of the mucous membrane was 



excluded. Their conclusions were based on the absence 

 of radiopaque material in the mucous membrane 

 of stomach injected immediately after surgical re- 

 moval. They suggest that the injected material flowed 

 from arteries of the submucosal plexus to the gastric 

 veins directly through a shunt located in the sub- 

 mucous plexus. In 1952, Walder (125), accepting the 

 presence of arteriovenous anastomoses in the sub- 

 mucous layer of the human stomach after what seemed 

 to be confirmation of them by Barlow (8) through 

 microdissection, carried out investigations to deter- 

 mine their function, size, and responses to stimuli, 

 both physical and pharmacological. Cannulation of 

 the right gastroepiploic artery and its accompanying 

 vein permitted him to introduce glass beads, 40 to 200 

 11 in diameter, into the artery and to recover them in 

 the venous outflow. The presence of spheres, 1 40 n in 

 diameter, in the venous outflow was believed to be 

 indicative of patent arteriovenous anastomoses, be- 

 cause spheres of this size could not travel through 

 the capillary network. The results of the injection of 

 drugs, nerve stimulation, and varying perfusion pres- 

 sures to determine their influence on the size of the 

 arteriovenous anastomoses were inconclusive. 



In an extensive study of the vascular patterns in the 

 alimentary canal, Barlow (8), in describing the arte- 

 rial supply to various portions of the stomach, notes 

 frequent anastomoses of the arteries in the submucous 

 plexus and the mucosa. The mucosal arteries give 

 rise to capillaries which also have anastomotic connec- 

 tions. He found arteriovenous anastomoses in the 

 stomach which consisted of an arterial end, variable in 

 length, a short narrow junction area, and a short 

 wide venous channel. This structure was demon- 

 strated by Barlow's double injection technique. The 

 arterial end may be a direct branch of a mucosal 

 artery or arise from a main channel in the submucous 

 plexus. It terminates by joining either a distant mu- 

 cosal vein or may double back on itself and anasto- 



