Skeletopy of the medullary cone in Sapajus apella: Clinical implications in epidural anesthesia / Esqueletopia do cone medular em Sapajus apella: Implicações clínicas na anestesia epidural

This work aimed to describe the skeletopy of the medullary cone of the capuchin monkey (Sapajus apella) and to lay morphological foundations to propose a route of administration for epidural anesthesia. We used five females adults S. apella, and dissected them to study their medullary cone. The fixated animals were dissected, a skin incision was made from the dorsal median line, epaxial musculature and vertebral arcs was removed to expose the spinal cord, individualizing the medullary cone and the lumbar intumescence. The base of S. apella medullary cone was located near the L5 vertebra and the apex near S3, the structure was 4.5 cm in average. The evaluated specimens presented five lumbar and four sacral vertebrae. We concluded that the positioning of S. apella medullary cone is caudally than in other species, suggesting that the most appropriate location for epidural anesthetic procedures is the sacrocaudal region.

Este estudo visa descrever a esqueletopia do cone medular em macaco prego (Sapajus apella), com a intenção de estabelecer bases morfológicas para prestar o apoio à implementação de procedimentos anestésicos e outros procedimentos de rotina clínica-cirúrgica veterinária, dada a crescente importância do papel do veterinário na saúde dos animais selvagens. Cinco S. apella adultos fêmeas foram utilizadas neste trabalho e dissecados para o estudo do cone medular. Os animais fixados foram dissecados, foi feita uma incisão na pele na linha média dorsal, a musculatura epaxial e os arcos vertebrais foram removidos para exposição da medula espinhal, individualizando o cone medular e a intumescência lombar. A base do cone medular do S. apella foi observada na altura da vértebra L5 com o ápice em S3, com comprimento médio de 4,5 cm. Os espécimes avaliados apresentaram cinco vértebras lombares e quatro sacrais. Conclui-se que o posicionamento do cone medular do S. apella é mais caudal em relação às outras espécies. Por conseguinte, é sugerido que o local mais apropriado para o procedimento anestésico peridural é a sacrocaudal região.

Anatomia do cone medular aplicada à via epidural de administração de fármacos em macacos-prego (Sapajus libidinosus) / Anatomy of the medullary conus applied to the epidural route of administration of drugs in capuchin monkeys (Sapajus libidinosus)

Com este estudo objetivou-se descrever a topografia do cone medular do macaco-prego (Sapajus libidinosus) a fim de fornecer suporte para que a realização de procedimentos anestésicos, bem como exames de mielografia e coleta de líquor, dentre outros procedimentos que utilizam a via epidural. Para tanto foram dissecados oito animais, sendo seis machos e duas fêmeas, de diferentes faixas etárias. Rebateu-se a pele para retirada da musculatura da região dorsal, exposição de toda a coluna vertebral e identificação das vértebras lombares e sacrais. Para estabelecer o final da medula espinhal e medir o comprimento do cone medular, foi aberto todo o canal vertebral lombossacro, seccionando-se lateralmente os arcos vertebrais. Em seguida a duramáter foi seccionada para visualização do cone medular e observação da relação topográfica deste com as vértebras. Todos os animais apresentaram cinco vértebras lombares e três vértebras sacrais. As vértebras se apresentaram, de forma geral, muito próximas e com os processos espinhosos bem desenvolvidos e direcionados em sentido cranial. O cone medular dos macacos-prego situou-se entre as vértebras L2 e L5, com a base localizando-se com maior frequência na altura da vértebra L3, enquanto o ápice em L4. O comprimento corporal (espaço interarcual occiptoatlântico até o espaço interarcual sacrocaudal) variou de 22,9 a 31,8cm, com média de 27,44 ±3,1cm enquanto que comprimento do cone medular variou de 1,70 a 3,51cm, com média de 2,47 ±0,57cm. Não houve correlação entre o tamanho do corpo e o comprimento do cone medular (r = 0,212). Conclui-se que apesar das variações do comprimento e posicionamento do cone medular, o seu ápice não ultrapassa a articulação lombossacral, tornando seguro o acesso ao espaço epidural por esta via.(AU)

This study aimed to describe the topography of the conus of capuchin monkey (Sapajus libidinosus) to provide support for anesthetic procedures, as well as examinations of myelography and CSF collection, among other procedures using the epidural route. Eight animals were dissected, six males and two females, of different ages. The skin was countered for removal of the dorsal musculature for exposure of the entire spine and identification of the lumbar and sacral vertebrae. To establish the end of the spinal cord and to measure the length of the conus medullaris, we opened the lumbosacral spinal canal through side section of the vertebral arches. The dura mater was sectioned to visualize the conus and to observe the topographical relation with the vertebrae. All animals showed five lumbar vertebrae and three sacral vertebrae. The vertebrae were in general very closed with the spinous processes well developed and directed cranially. The conus of capuchin monkeys was located between the L2 and L5 vertebrae, with the base mostly in the L3 vertebra, and the peak in L4. The body length (interarcual space occiptoatlântico until sacrocaudal interarcual space) ranged from 22.9 to 31.8cm, with a mean of 27.44±3.1cm while the medullary cone length ranged from 1.70 to 3.51cm, with a mean of 2.47±0.57cm. There was no correlation between body size and length of the medullary cone (r=0.212). It is concluded that despite the variations in length and positioning of the medullary cone, its height does not exceed the lumbosacral joint, making safe access to the epidural space in this way.(AU)

The retinal ganglion cell classes of New World primates

In the primate retina there are distinct ganglion cell classes, exhibiting paarticular morphologies and central projections, each responsible for conveying particular types of visual information to the brain. The chief retinal imputs to the cortex arise from specific ganglion cell classes, M-ganglion cells, responsible for carrying the luminance signal, and P-ganglion cells, that convey the red-green color oppnent signal, as well as high contrast luminance signal. There are other ganglion cell classes, such as small-field bistratified cells, exhibiting dentrites that stratify at two different levels in the inner plexiform layer, which convey the blue-yellow color oppnent signal. Most published data concerning primate retinal ganglion cell anatomy and physiology have been obtained from Old World species. Studies on New World monkeys have recently become of interest since they differ from the Old World monkeys with respect to the color vivion inheritance pattern. On reviewing retinal ganglion cell layer organization in New World monkeys, it seems that there are more similarities than differences in relation to the Old Work monkeys. Diurnal genera of New World monkeys exhibit a well-developed fovea centralis and ganglion cell density peak, as well as peripheral density values which are in the range reported for Old World monkeys and human. Moreover, all the major ganglion cell classes identified in Old World monkeys are also present in New World primates. Up to now, no obvious anatomical differences between dechromats and trichromats have been reported. The only genus that is significantly different from the others is the Aotus. It exhibits lower ganglion cell density in the central retina, and apparently lacks the small-field bistratified cells.