Vessels involved in the venous outflow from glandular mucosa of hamster stomach.

Blood from the glandular part of hamster gastric mucosa is drained by collecting venules, running from the subepithelial layer towards lamina muscularis mucosae. To visualise vessels involved in the venous outflow, hamsters were exposed to atropine and subjected to intravital ligation of portal vein, causing strong hyperaemia. Distribution of vessels and their connections were studied a) in translucent, flat preparations of the glandular stomach, b) in thick sections of glandular mucosa cleared in the mineral oil, and c) in semi-thin plastic or paraffin sections. Collecting venules were drained by single vessels running parallel to the lamina muscularis mucosae (paramuscular venules), which, in turn, joined submucosal veins through openings in muscularis mucosae. Moreover, some collecting and paramuscular venules discharged into venules belonging to vascular triples composed of two venules and arteriole. The triplets were also parallel to muscularis mucosae. Triplets did not form connections with submucosal veins but passed on the abluminal surface of muscularis mucosae. Thus, some structural elements involved in venous outflow from glandular gastric mucosa differ from those in rats, in which vascular triplets were absent and all collecting venules drained into single paramuscular vessels. Contraction/relaxation of muscularis mucosae may regulate the amount of blood present in the venous system of the mucosa and the diameter of venules. Rhythmical changes of the latter could cause changes in intramucosal pressure, affecting movement of tissue fluid in the mucosa and thus the function of gastric cells.