Distribuição das artérias mesentéricas cranial e caudal na nutria (Myocastor coypus)

Abstract

Background: The nutria (Myocastor coypus) is a semi-aquatic rodent, originating from the extreme south of South America, exploited for commercial purposes, in particular the quality of your skin and fl esh. The objective of this study was to systematize and describe the cranial and caudal mesenteric arteries in the nutria. Materials, Methods & Results: To perform this study were used a total of 30 specimens of nutria, 15 females and 15 males. To the animals were administered heparin and after thirty minutes Thiopental Sodium, via an intraperitoneal injection, to perform euthanasia. The thoracic cavity was opened ventrally in plastron, the thoracic aorta was cannulated and the system was washed with saline solution. Then the system was fi lled with latex 603 colored in red and the animals remained immersed in running water for one hour. The skin was removed and then the trunk was transversally sectioned near the last thoracic vertebrae. The abdominal cavity remained closed and formaldehyde was administered via an intraperitoneal injection. The specimens were fi xed in formaldehyde for seven days, the abdominal cavity was opened, the viscera were removed in block and the arteries were dissected. Statistical analyses of the results were performed using percentage values. It was observed that the abdominal aorta gave rise to the cranial and caudal mesenteric arteries. The cranial mesenteric artery originated as a standard the caudal pancreaticoduodenal, middle colic, right colic, ileocolic, jejunal arteries and ileal branches. The pancreaticoduodenal artery traveled the interior of mesoduodeno irrigating part of the body and the right lobe of the pancreas and the end of the duodenum. The middle colic artery bifurcated into right and left branches, going to irrigate the transverse and descending colon, respectively. The right colic artery gave a branch to the beginning of the ascending colon, small branches to the transverse colon and continued going through the loop formed by the ascending colon. The ileocolic artery emitted the cecal artery, ileal, ascending colic and cecum branches, for irrigation of the cecum, ileum and ascending colon. The jejunal arteries were responsible for the irrigation of the jejunum, ileum, and the last jejunal artery anastomosed with the ileal artery. The caudal mesenteric artery originated the left colic and cranial rectal arteries. Discussion: In this study and in others papers of nutria and chinchilla, we observed the cranial mesenteric artery originating from the abdominal aorta caudally to the celiac artery. The sequences of the origin of the branches of the cranial mesenteric artery were varied between rodent species and within them. In this study, and in another one of nutria, the caudal pancreaticoduodenal artery was predominantly double. In rodents, the middle colic artery was originated, as standard, from the cranial mesenteric artery, but this study showed that in one piece, this artery originated from the ileocolic artery. The terminal branch of middle colic artery was anastomosed in osculum with the left colic artery, branch of the caudal mesenteric artery in 46,7% of the sample, and this observation was also found in another articles of nutria (30%) and agouti (36,3%). The right colic artery emitted a colic branch to the top of the ascending colon and anastomosed in osculum to the colic branch of the ileocolic artery in 46.7% of the animals, and this anastomosis was also observed in agouti. The number of jejunal arteries varied widely inside and within species of rodents. The ileocolic artery vascularized the cecum, ileum and ascending colon in nutrias and agouti. The caudal mesenteric artery bifurcated into the left colic and cranial rectal artery in nutrias, agoutis, chinchi