Banca: Amilton Vallandro Marçal (PUC-RS Uruguaiana), Luciana Silveira Flores Schoenau (UFSM), Maria Cristina Faccioni Heuser (UFRGS).Neste trabalho estudou-se as artérias da base do encéfalo e suas fontes de suprimento sangüíneo em nutria (Myocastor coypus). Foram utilizados 32 espécimes. Em 30 animais, o sistema arterial foi preenchido com látex 603 corado em vermelho através da artéria aorta. Duas fêmeas foram utilizadas na confecção de moldes acrílicos. Sistematizou-se a origem das fontes de suprimento sangüíneo para o encéfalo e as artérias (Aa) da face ventral do cérebro, à direita (D) e à esquerda (E), com suas respectivas percentagens de aparecimento. O arco aórtico emitiu o tronco braquiocefálico e a artéria (A.) subclávia E (60%) ou tronco braquiocefálico, A. carótida comum E e A. subclávia E (40%). O tronco braquiocefálico lançou A. carótida comum D e E e A. subclávia D (60%) ou A. carótida comum D e A. subclávia D (40%). A A. carótida comum D e E dividiu-se em A. carótida externa e A. occipital. A A. carótida interna foi ramo da A. occipital (100%), à D e E, e não cooperou na irrigação encefálica. Ramos terminais das Aa. Vertebrais D e E presentes (100%) formaram a A. basilar (100%). A. espinhal ventral presente (100%).A. cerebelar caudal à D foi simples (60%), dupla (36,7%) e tripla (3,3%), e à E foi simples (60%) e dupla (40%). A. cerebelar média como ramo da A. cerebelar caudal à D (70%) e à E (73,3%). A. trigeminal D e E ímpar (100%). A. cerebelar rostral D, simples (73,3%) e dupla (26,7%), à E, simples (70%) e dupla (30%). A. cerebral caudal D, simples (66,7%) e dupla (33,3%), à E, simples (73,3%) e dupla (26,7%). A. hipofisária D e E ímpar presente (100%). A. cerebral média D e E ímpar presente (100%). A. cerebral rostral D, desenvolvida e ímpar (86,7%), dupla (10%) e ausente (3,3%), à E desenvolvida e ímpar (100%). Ramo medial da A. cerebral rostral D, ímpar e desenvolvido (66,7%), vestigial (23,3%) ou ausente (10%), à E, ímpar e desenvolvido (73,3%), vestigial (23,3%) e ausente (3,3%). A. inter-hemisférica rostral presente (100%), formada pela anastomose do ramo medial da A. cerebral rostral D e E (40%), formada apenas pelo ramo medial da A. cerebral rostral E (33,3%) e formada apenas pelo ramo medial da A. cerebral rostral D (26,7%). A. lateral do bulbo olfatório D e E presente e ímpar (100%). A. medial do bulbo olfatório D e E ímpar (100%). A. etmoidal interna D simples (96,7%) e dupla (3,3%), à E, simples (100%). Observou-se que o círculo arterial cerebral da nutria foi fechado caudalmente (100%) e rostralmente aberto (60%) ou fechado (40%). O encéfalo foi suprido exclusivamente pelo sistema vértebro-basilar.

Neste estudo, utilizaram-se 30 nutrias, 15 fêmeas e 15 machos, com o sistema arterial aórtico-abdominal preenchido com látex 603, pigmentado em vermelho, e fixado em uma solução aquosa de formaldeído a 20%. A aorta abdominal emitiu de sua superfície dorsal de 6 a 8 artérias lombares únicas. Das artérias renais, direita e esquerda, originaram-se as artérias frênico-abdominal para irrigar parte do diafragma e da parede abdominal lateral cranial. A aorta abdominal lançou dorsalmente, a artéria sacral mediana, cranialmente a sua bifurcação em artérias ilíacas comuns. As artérias ilíacas comuns, ramos terminais da aorta abdominal, originaram as artérias ilíacas interna e externa. A artéria ilíaca interna distribuiu-se nas vísceras da cavidade pélvica. A artéria ilíaca externa emitiu uma artéria umbilical e, antes de alcançar o anel femoral, lançou a artéria circunflexa ilíaca profunda para a parede abdominal lateral, em seus dois terços caudais. A artéria ilíaca externa lançou o tronco pudendo-epigástrico, que originou a artéria epigástrica caudal, para a parede abdominal ventral e a artéria pudenda externa, que saiu pelo canal inguinal, para irrigar a genitália externa. Os ramos parietais diretos da aorta abdominal foram as artérias lombares e a artéria sacral mediana, enquanto as artérias frênico-abdominal, circunflexa ilíaca profunda e epigástrica caudal, foram ramos colaterais parietais indiretos. Os ramos terminais da artéria aorta abdominal foram as artérias ilíacas comuns com seus ramos, as artérias ilíacas interna e externa.

Ramos colaterais viscerais da artéria aorta abdominal em Myocastor coypus (nutria) The collateral visceral branches of the abdominal aorta in Myocastor coypus (nutria) Paulete de Oliveira Vargas Culau 1 , Rodrigo Cavalcanti de Azambuja 2 & Rui Campos 1 RESUMO A nutria é um roedor originário do extremo sul da América do Sul explorado comercialmente por sua pele e carne. Neste trabalho, sistematizou-se os ramos colaterais viscerais da aorta abdominal. Utilizaram-se 30 nutrias, 15 fêmeas e 15 machos, com o sistema arterial aórtico-abdominal preenchido com látex 603. A aorta abdominal emitiu ventralmente como ramo colateral visceral à artéria celíaca, que se trifurcou nas artérias gástrica esquerda, hepática e lienal. Os ramos da artéria celíaca promoveram a irrigação do estômago, duodeno, fígado, pâncreas e baço. A seguir, a aorta abdominal emitiu a artéria mesentérica cranial, de calibre maior que a artéria celíaca, justaposta caudalmente. A artéria mesentérica cranial emitiu ramos, vascularizando a parte final do duodeno, lobo direito do pâncreas, jejuno, íleo, ceco, cólon maior e cólon menor. A aorta abdominal emitiu lateralmente as artérias renais direita e esquerda. As artérias adrenais foram ramos colaterais diretos das artérias renais e/ou da artéria frênico-abdominal. A artéria mesentérica caudal foi emitida da superfície ventral da aorta abdominal, próximo à sua bifurcação em artérias ilíacas comuns. A artéria mesentérica caudal lançou ramos para o cólon menor e porção cranial do reto. Os ramos colaterais viscerais diretos da aorta abdominal foram: artéria celíaca, artéria mesentérica cranial, artérias renais e artéria mesentérica caudal. Os ramos viscerais indiretos foram: artérias adrenais e artéria umbilical. A artéria ilíaca externa emitiu a artéria umbilical que irrigou a bexiga, e continuou-se como uma grande artéria uterina, nas fêmeas, irrigando todo o útero, inclusive os ovários e, nos machos, a artéria testicular, que irrigou o testículo.

Ramos colaterais do arco aórtico e suas principais ramificações em nutria (Myocastor coypus)Collaterals branches of the aortic arch and its main rami in nutria (Myocastor coypus) ABSTRACT Background: Nutria (Myocastor coypus), also known as Swamp Beaver, is a medium-sized semiaquatic rodent that belongs to the Capromyidae family. Originally from the southernmost part of South America, the species is distributed in several parts worldwide such as Europe and United States, where it has been used for commercial purposes due to the excellent quality of its fur and meat. Information about the nutria morphology is rare. Only a few articles about its abdominal aorta branches can be found, but nothing exists regarding its aortic arch. Consequently, other rodents such as chinchillas, agoutis, guinea pigs capybaras, pacas and rats will be used in the discussion. Therefore, this study aims to obtain morphological information that could justify such discussions in a functional point of view, and that could result in support for a better understanding of the physiology of this animal. Materials, Methods & Results:Thirty-two Myocastor coypus were used in the study, originated from a breeding facility in the town of Caxias do Sul, RS and authorized by IBAMA. The animals were put to sleep by means of an anesthetic overdose administrated intraperitoneally, and kept in formaldehyde for seven days to be subsequently dissected. After having their arterial system flushed with saline solution, the aorta of thirty specimens received an injection containing latex 603 through the left ventricle, for later observation of the arteries of the cranial mediastinal space and neck. Dental resin was injected in two specimens, for subsequent manufacture of molds by means of maceration. Schematic drawings of all parts were made with the help of a magnifying glass, for posterior composition of results. The brachiocephalic trunk and the subclavian artery arose in sequence from the aortic arch of the nutria in 60% of the samples, whereas the brachiocephalic trunk, left common carotid artery and left subclavian artery arose from the arch in 40% of the samples. The branching sequence of the collateral branches of the subclavian arteries showed a great variation, presenting isolated vessels and forming trunks among the arteries identified (according to the tables). The thoracic vertebral, vertebral, internal thoracic, dorsal scapular arteries and the superficial-deep cervical trunk aroused medially from the right subclavian artery towards a lateral direction, as main collateral branches of highest prevalence. On the other hand, the left subclavian artery also gave off the vertebral artery as its first vessel, followed by the internal thoracic and thoracic vertebral arteries, and its last collateral branch was a common trunk between the dorsal scapular artery and the superficial-deep cervical trunk. Discussion: Other rodents in the study presented the same aortic arch sequence as observed in nutrias i.e., the brachiocephalic trunk and the left subclavian...

Background: The nutria (Myocastor coypus) is a medium-size, semi-aquatic rodent, valued in skin and meat industry. The brain circulation has been well studied in rodents but not in nutria. To understand and compare the phylogenetic development of the arteries of the base of the brain in rodents, this paper aims to describe and systematize these arteries, establishing a standard model and its main variations in nutria.Materials, Methods & Results: Following approval by the Ethics Committee of Federal University of Rio Grande do Sul, thirty nutrias from a commercial establishment authorized by Brazilian Institute of Environment and Natural Resources (IBAMA) were studied. For euthanasia, was applied heparin (10000 U.I for animal), intraperitoneally, and after thirty minutes the animals ware sedated with acepromazine (0.5 mg/kg) and meperidine (20 mg/kg), intramuscularly. After sedation, they were euthanized with thiopental sodium (120 mg/kg) and lidocaine (10 mg/mL), intraperitoneally. The heart was accessed, the cardiac apex was sectioned, the aorta was cannulated via the left ventricle and clamped close to the diaphragm, and the arterial system was washed with saline solution and filled with latex. The animals were submerged in water for latex polymerization, the trunk was sectioned, the skin removed and a bony window was opened in the skull vault. The pieces were fixed in formaldehyde. The brains were removed, and schematic drawings of the arteries from the base of the brain were made for elaboration of the results. The nutria’s brain was vascularized by the vertebro-basilar system. The terminal branches of the right and left vertebral artery were anastomosed on the ventral surface of the medulla oblongata, forming the basilar artery, and caudally the ventral spinal artery. The basilar artery formed collateral branches, the caudal and middle cerebellar and trigeminal arteries, and at the height of the rostral pons groove, divided into its two terminal branches, the rostral cerebellar and cerebral caudal arteries. The terminal branches of the basilar artery projected rostrally, forming the hypophyseal and rostral choroid arteries. The basilar artery passed the optic tract and bifurcated in the middle cerebral artery, its last collateral branch, and in the rostral cerebral artery, its terminal branch. The rostral cerebral artery formed the medial branch, closing the cerebral arterial circle caudally in 40% of the cases.Discussion: In rodents, variability of the cerebral arterial circle was observed due to the degree of atrophy of the internal carotid artery. The basilar artery was a rectilinear vessel of great caliber in all described rodents, and in rodents with a vertebro-basilar system, it was divided into its terminal branches after crossing the pons, forming the rostral cerebellar, hypophyseal, rostral choroid, caudal, middle and rostral cerebral arteries. The caudal cerebellar artery had variation of origin and sometimes duplication. The median cerebellar artery, a collateral branch of the caudal cerebellar artery, was a branch of the basilar artery in capybara. The caudal cerebral artery had variations between rodents. In capybara, chinchilla and nutria the middle cerebral artery was the collateral branch of the terminal branches of the basilar artery, and distributed on the convex surface of the cerebral hemisphere. The rostral cerebral artery, a branch of the terminal branch of the basilar artery, was a branch of the internal carotid artery in other rodents, forming the medial branch, which was anastomosed with that of the opposite antimer, when present, forming the rostral communicating artery. In nutria, the cerebral arterial circle was closed caudally in all cases, as in other rodents, however, it was opened rostrally in 60% of cases, compared to 70% in chinchilla and 10% in capybara.

The nutria (Myocastor coypus) is a medium-sized, semi-aquatic rodent valued by the skin and meat industry. This study aimed to describe and systematize the caudal cerebral artery on the brain surface in nutria, establishing a standard model and its main variations in this species. The thirty animals used were euthanized according to animal welfare rules. The vessels were filled with latex stained with red pigment and the samples were fixed in formaldehyde. In nutria, the brain was vascularized by the vertebral basilar system. The terminal branches of the basilar artery originated the rostral cerebellar, caudal cerebral, rostral choroidal and middle cerebral arteries, and its terminal branch, the rostral cerebral artery. The terminal branch of the basilar artery projected the caudal cerebral artery, which is usually a single medium-caliber vessel, into the transverse fissure of the brain. The caudal cerebral artery was presented as a single (66.7% of the cases to the right and 76.7% to the left) and double vessel (33.3% of the cases to the right and 23.3% to the left). It originated the rostral mesencephalic artery, the proximal component, and the caudal inter-hemispheric artery. The terminal branches of the rostral and caudal tectal mesencephalic arteries formed a typical anastomotic network. The caudal inter-hemispheric artery emitted central branches, the caudal choroidal artery, hemispherical occipital arteries, rostral tectal mesencephalic branches and distal components, and anastomosed “in osculum” with the terminal branches of the rostral inter-hemispheric artery. The caudal choroidal artery anastomosed with the rostral choroidal artery, where it branched out on the thalamic mass, vascularizing all diencephalic structures and the hippocampus. The caudal cerebral artery and its terminal branches anastomosed with the terminal branches of the rostral and middle cerebral arteries in a restricted region of the caudal pole of the cerebral hemisphere. The vascularization area of the caudal cerebral artery and its central branches in the paleopallial of the piriform lobe is extremely restricted, caudomedially.