The red-rumped agouti, a small, wild rodent belonging to the Dasyproctidae family, has great zootechnical potential and adapts well to captivity. In order to contribute to the knowledge regarding the neuroanatomy of the species, the aim of this study was to describe the origin of the nerves forming the lumbosacral plexus by evaluating 12 animals (six males and six females) that had been used in previous experiments. Animals were fixed in a 10% aqueous formaldehyde solution and eviscerated after 72 hours. Major and minor psoas muscles were then retracted to expose the nerves forming the plexus, and the plexus was bleached via cotton soaked in 20-volume hydrogen peroxide for 12 hours for subsequent dissection. Topographical relations of the lumbosacral plexus were grouped into tables and arranged in terms of simple percentages. In seven cases (58.34%), the lumbosacral plexus in the red-rumped agouti stemmed from the ventral roots of the last four lumbar nerves and the first three sacral nerves (Type I: L 4 -S 3 ). In four animals (33.33%), the lumbosacral plexus stemmed from L 5 -S 3 (Type II), and in one case (8.33%) it stemmed from L 5 -S 4 (Type III). Together, our observations demonstrated that the lumbosacral plexus of the red-rumped agouti comprised the lateral femoral cutaneous, genitofemoral, femoral, obturator, sciatic, cranial gluteal, caudal gluteal, and pudendal nerves. Finally, the origin of the lumbosacral plexus and its constituent spinal nerves was similar to what has been described in other rodents, including the rock cavy, lowland paca, and Spix's yellow-toothed cavy. Key words: Anatomy. Dasyprocta leporine. Nerves. Nervous system. Rodent. ResumoA cutia é um roedor silvestre, de pequeno porte pertencente à família Dasyproctidae, com grande potencial zootécnico e que se adapta bem ao cativeiro. De forma a contribuir acerca da biologia da espécie, objetivou-se descrever a origem dos nervos que formam o plexo lombossacral. Foram utilizados 12 animais (6 machos e 6 fêmeas), provenientes de experimentos anteriores. Os animais foram fixados em solução aquosa de formaldeído a 10% e após 72 horas, eviscerados. Em seguida os músculos psoas maior e menor foram rebatidos, expondo-se os nervos que formavam o plexo. Sobre estes nervos foi colocado algodão embebido com peróxido de hidrogênio a 20 volumes, permanecendo por 12 horas seguidas para clareamento e consequente dissecação. As relações topográficas do plexo lombossacral agrupadas em tabelas em forma de porcentagem simples. O plexo lombossacral da cutia originou-se em sete casos (58,34%) a partir das raízes ventrais dos quatro últimos nervos lombares e três primeiros nervos sacrais (Tipo I -L 4 -S 3 ), em quatro animais (33,33%) a partir de L 5 -S 3 (Tipo II) e um caso (8,33%) a partir de L 5 -S 4 (Tipo III). Os nervos que participaram do plexo lombossacral da cutia foram: cutâneo femoral lateral, genitofemoral, femoral, obturatório, isquiático, glúteo cranial, glúteo caudal e nervo pudendo. A origem do plexo lombossacral e os nervos espinhais c...

Detailed knowledge of the arterial system is an important prerequisite when interpreting experimental data in research, as well as in the diagnosis of cardiovascular disease using imaging techniques such as Doppler echocardiography and contrast radiography. Thus, considering the importance of the aortic arrangement, the objective of this study was to describe the collateral arteries of the aortic arch of agoutis in order to establish the standard model, and therefore contribute to studies involving research related to heart disease, and produce information for a more accurate diagnosis in complementary imaging examinations. In this study, 14 adult animals were used, comprising eight males and six females. The vascular system was washed with 0.9% aqueous saline solution and perfused with Neoprene 450 latex coloured with yellow or red pigment, which was subsequently dissected and analysed. One male animal was used for the digital contrast radiography technique perfused with a liquid barium sulphate solution (Bariogel®) (1 g/ml) and Neoprene 450 latex, both diluted 1/3. The aortic arch of the agouti presented with only the brachiocephalic trunk as collateral branch in all the animals studied. Thus, agouti falls into type 1 for mammalian aortic arch vascular arrangements.