Avaliação morfológica de corpo caloso e córtex cerebral em delfinídeos

Abstract

Cetaceans are represented by dolphins (Odontoceti) and whales (Mysticeti) and are characterized as mammals with life totally adapted to the aquatic environment. Odontocetos have significant encephalization, showing a brain developed in shape and size. Detailed descriptions of the macroscopic morphology of the brain of these animals is hard to obtain. Therefore, the present work aims to evaluate morphologically brain structures, emphasizing the corpus callosum and cerebral cortex of two individuals of Odontoceti group - the species Feresa attenuata and Stenella attenuata. For this, were collected by necropsies, the brains of dolphins stranded dead in early stages of decomposition. The area comprised the beaches of Rio Grande do Norte between 2016 and 2017. The material of study was fixed in 10% formaldehyde, and then heavy. The analyses were performed by using coronal sections, where the structures of interest were measured with a software. It is relevant to point out that brain of Odontocetos is one of the largest found in all animals, if compared in proportion to the body. In relation to the species analyzed, the brain of Feresa attenuata presented larger dimensions and greater brain mass than Stenella attenuata. In addition, the Corpus Callosum turned out to be a structure with little development in Odontocetos. In relation to the cerebral cortex of this group, it presented greater thickness in regions that comprise the pre motor and motor cortex. Finally, it is important to mention that all the features of the neuroanatomy of Odontocetos are related with the physiology and the behaviour of these animals.