THE MICROVASCULAR ARCHITECTURE OF RAT PROXIMAL DUODENUM, WITH PARTICULAR REFERENCE TO BRUNNER’S GLANDS1

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Abstract
The microvascular architecture of rat duodenal mucosa was investigated by scanning electron microscopy of vascular corrosion casts, and of fractured tissue specimens in which the interstitial matrix had been digested by acid/enzyme treatment. Light microscopy of cleared tissues, in which the vasculature was injected with silicone elastomer, was used to define the spatial organization of the larger supply/drainage vessels. Within the mass of Brunner''s glands, possibly because of its compact nature, it was impossible to define differing microvascular networks related to particular functional regions of the glands (acini and ducts). The microvascular bed of Brunner''s glands is clearly a separate vascular bed from that of the rest of the duodenal mucosa and is arranged essentially in parallel to it; it is argued that this separation of venous outflow from the glands may be important in maintaining the HCO3- protection of the duodenal surface from acid erosion. Microvascular architectural differences in the villi and intestinal gland regions, compared to more distal rat small intestine, include an apparently denser villus subepithelial capillary network origin of villus venules closer to the villus tip and frequent direct drainage of the pericryptal network into adjacent venules.