Ramos colaterais parietais e terminais da aorta abdominal em coelhos da raça Nova Zelândia (Oryctolagus cuniculus)

Abstract

Background: Rabbits (Oryctolagus cuniculus) are lagomorphs belonging to the Leporidae family. They are an important source for humans feeding industry and widely used in laboratory experiments. In the biomedical investigation fi eld, the rabbit contributes for the production of several scientifi c studies. Since information about the rabbit’s morphology is rare, especially what refers to abdominal vascularization, this work had the objective to systematize and describe the parietal collateral and terminal branches of the abdominal aorta in New Zealand rabbits. Materials, Methods & Results: Fourteen male and sixteen female New Zealand young adult rabbits (Oryctolagus cuniculus) were used. Animals were euthanized with T 61, administered via an intrapulmonary injection. Skin was removed, thoracic cavity opened in plastron, thoracic aorta cannulated, according to blood fl ow, and the two cranial and caudal cava veins sectioned near the heart. System was washed with saline solution and heparin and fi lled with red latex. Animals remained immersed in running water, for 90 min, and the trunk was transversally sectioned, near the last thoracic vertebra. The abdominal cavity remained closed and formaldehyde was administered via an intraperitoneal injection. Samples were fi xed in formaldehyde for seven days, the abdominal cavity opened, the viscera removed in block and the arteries dissected. Schematic drawings of every preparation were made-up and the parietal and terminal branches of the abdominal aorta systematized. Statistical analysis of the results was performed using percentage values. The direct parietal collateral branches of the abdominal aorta were the lumbar arteries, while the indirect collateral branches were the cranial phrenic, phrenicoabdominal and deep iliac circunfl ex arteries. The terminal branches of the abdominal aorta were the right and left common iliac arteries, and each one gave off the internal iliac artery and continued as external iliac artery. The median sacral artery was not considered a terminal branch like in other mammals, but a collateral branch. Discussion: In nutria, from six to eight single lumbar arteries were given off from the dorsal surface of the abdominal aorta. In this study, it was observed that almost every lumbar arteries were single, except for the fi rst vessel, which in 50% of the cases was double. The literature does not describe the formation of the phrenicoabdominal artery, in the rabbit. The cranial abdominal artery was described as a branch of the corresponding renal artery, and the caudal phrenic artery was given off from the dorsal surface of the abdominal aorta or sometimes, together with the last dorsal intercostal artery. In our study, it was observed that the caudal phrenic and cranial abdominal arteries were collateral branches of the phrenicoabdominal artery, which was a branch of the renal artery. The median sacral artery, in nutria, was originated from the dorsal surface, cranially to the aorta’s bifurcation, being considered a collateral branch like observed in rabbits. As opposed to nutria, in which the deep iliac circunfl ex artery was branch of the external iliac artery, in the rabbit it was generally a branch of the common iliac artery. In rabbits, the terminal branches of the abdominal aorta, the common iliac arteries and the internal and external iliac arteries, were similar to literature’s reports in rats and in nutria.