[The comparative anatomical characteristics of the arteries and the microcirculatory bed of the duodenum].

Morphological characteristics of comparative-anatomical formation of extra-organic and organic arteries and microcirculatory bed architectonics in duodenum of 312 certain representatives of all classes of vertebrates was given. It was shown that two groups of vessels qualitatively different in form and type of branching formed in the process of historical development: arteries with magistral-arcuate form of branching of non-anastomosing type and that with magistral-annular form of branching. The appearance of arterio-venular anastomosis type junctions in latter ones between one side of the intestine and veins of the opposite side provides the phenomenon of bilateral non-capillary countercurrent organic circulation. Microcirculatory bed of part of the villi completely lacked capillaries, while arterioles were connected with venules expertionally by arterio-venular anastomoses.