Veins with saccular dilatations in gastric mucosa of the rat

It is well known that blood from the gastric mucosa of the rat is drained by collecting veins (venules). The aim of this study was to describe hitherto unrecognized saccular dilatations connected with these vessels. Rats received atropine or papaverine l h before ligation of the portal vein, Stomachs fixed in formaldehyde were prepared in toto after clearing in methyl salicylate or processed by standard histological technique. A single stomach contained about 1000 connecting veins localized exclusively in the oxyntic mucosa. After administration of relaxing agents and portal vein ligation the collecting veins were enlarged and in 80 percent of them one to three sacculi filled with blood could be seen. Histological observations shown that collecting veins empty into veins running between lamina muscularis and lamina propria mucosae. Sacculi were partially separated from the lumen of the collecting vein by a tissue band. In view of the relaxing effect evoked by atropine the veins and their sacculi appear to be under vagal control. Conceivably, their alternate expansion and collapse could facilitate movement of glandular content to the surface of the stomach and/or movement of interstitial fluid between cells.