Comparative anatomical study of the large intestine in rabbit and chinchilla

Anatomical particularities of the digestive tract in the rabbit and chinchilla require careful evaluation due the fact that these two species are used both as experimental model or pets. We studied the topography of large intestine in ten rabbits and ten chinchillas using regional and stratigraphic dissection. Focusing on anatomical particularities as well as differences, the aims of this study is an accurate description of lower digestive tract in rabbits and chinchillas. The large intestine has the same segments: cecum, colon and rectum. The cecum of the rabbit is large, show no muscular strips, containing 55% of dry matter of the large intestine, compared with chinchilla, in which the volume of the cecum containing 20% of dry matter of large intestine. Ascending colon of rabbit is very coiled, shows four segments: proximal one (ampula coli), 10 cm length, with three powerful muscular bands which separates rows of multiple haustra; the second portion has only one muscular band and fewer, smaller haustra; the third part (fusus coli) is short, about 4 cm length but high vascularizated and innervated; the fourth portion is very short and is open in descending colon. In chinchillas, ascending colon has three parts: proximal loop with two distinct areas, simple intermediate portion, and a long distal portion extending to the right colic flexure. The last segment consists of two parallel parts joined by an apical flexure. Transverse colon is very short both in rabbit and chinchilla. Rabbit descending colon is long and floating, show relative flexuous pattern with a dilated portion as a sigmoid colon. In chinchillas, descending colon forms numerous convolutions. The rectum is short and present paraproctitis glands in both species. Data presented in this study upgrade and systemize knowledge on lower digestive tract anatomy in lagomorphs and rodents. The results are important both in research and in clinical management of disorders involving the lower digestive tract.