Variability of ramification of the a. mesenterica cranialis in the domestic rabbit (Oryctolagus cuniculus f. domestica).

The authors studied the ramification of the a. mesenterica cranialis and its variability in 30 domestic rabbits (Oryctolagus cuniculus, f. domestica, breed New Zealand White). The animals were anaesthetized and red-dyed latex was injected into their arterial bed via the thoracic aorta. In every case (100%), the a. mesenterica cranialis was an independent trunk arising from the abdominal aorta 1.5-2 cm caudally to the origin of the a. coeliaca. We did not observe a truncus coeliaco-mesentericus in our material. In 17 cases (56.7%), the a. pancreaticoduodenalis caudalis was the first branch of the a. mesenterica cranialis. In 28 cases (93.3%) it formed a thick trunk which divided into two main branches to the aboral part of the duodenum and the caudal part of the pancreas respectively; in two cases (6.7%), the a. pancreaticoduodenalis caudalis was duplicated. In only two cases (6.7%), the first branch of the a. mesenterica cranialis was the a. colica media. The a. mesenterica cranialis then divided into two thick trunks to the intestine - the truncus jejunalis and the truncus ileocaecocolicus. Single aa. jejunales branched off successively from the arching truncus jejunalis. The truncus ileocaecocolicus led in a caudal direction and broke up, as a rule, into three arteries supplying the ileum, the caecum and the colon transversum. In 17 cases (56.7%), 1-6 aa. jejunales arose directly from the trunk of the a. mesenterica cranialis and 13-21 from the convexity of the arch of the truncus jejunalis. In 13 cases (43.3%), all the aa. jejunales found (11-23) were branches of the truncus jejunalis. On the mesenteric side of the jejunum, the aa. jejunales forked and formed an arcade from which small branches led to the intestine. In the rabbit we always observed only one arcade; more complex systems were not formed. A truncus ileocaecocolicus, whose branching was characterized by marked variability, was found in all 30 cases (100%). Division of this trunk to an a. ileocaecalis, a. caecocolica and a. colica dextra was observed in only four cases (13.3%). In every case, extensive anastomoses with branches of the a. colica dextra and a. colica sinistra were formed. In general, it can be claimed that the arterial bed of the a. mesenterica cranialis is highly variable. Since little attention has been paid in the literature to variability of the ramification of this artery in different species of mammals, the authors will concentrate, in their next studies, on a detailed investigation of the arterial bed of the abdominal cavity, and of its variability, in further laboratory animals.