Arterial supply to the pig intestine: an unusual pattern in the mesentery.

The arrangement of arteries in the mesentery in pigs was studied with latex casts and light microscopy. Arterial arcades, which are characteristic of the mesentery in man and other species, are absent. Instead, a narrow band of numerous, anastomosing arteries gives rise to up to about 500 bundles of arteries and accompanying veins, which radiate out in the mesentery. Each bundle contains up to 30 arteries, but these recombine as they approach the jejunum, and form 1-4 arteriae rectae. The significance of the very large number of small arteries in the mesentery is not known, but they may play a role in the control of blood pressure in the intestinal wall, or as sites of countercurrent exchange.