Estudo macroscópico do telencéfalo, da vascularização da base e seios da dura-máter em Alouatta belzebul
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2020-11-11
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Universidade Federal de Goiás
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Primates of the species Alouatta belzebul, also known as howler monkeys, guariba and barbado are endemic to Brazil, of large size, slow movements and quadrupedal locomotion. The knowledge of the morphology of this species is scarce and, in some aspects, as the brain is non-existent. The objective was to describe the macroscopic anatomy of Alouatta belzebul's telencephalon, as well as the vascularization of the base of the brain, nuclei of the base and the venous sinuses of the dura mater. Twenty specimens of Alouatta belzebul were studied, where the brain gyres and grooves were dissected, the base nuclei were identified and the arterial system and venous sinuses were perfused with the injection of colored latex. The telencephalon of A. belzebul presented lysencephalic characteristics, corroborating with several other species of non-human primates and differing from genera such as Pan and Homo. The nuclei of the base were quite evident and the caudate nucleus, putamen, pale medial globe and pale lateral globe, cloister and black substance have been described, which are functionally related to the motor behavior of the species. In the analysis of the encephalization index, it was observed that the Alouatta belzebul is phylogenetically closer to Sapajus and Macaca and more distant from genera such as Brachyteles and Callithrix, showing expressive cognition and intelligence. Regarding the inclination of the central groove, it was observed that in Alouatta belzebul the upper extremity is posterior to the lower extremity, data that corroborate with man, baboons and chimpanzees and reveal a large frontal lobe when compared to Sapajus libidinosus, showing the maximum development in these primates. The arterial circle of the Alouatta belzebul consists of two vascular systems: the vertebro-basilar and the carotid system, which anastomose to close the arterial circuit. In the caudal portion of the arterial circle are the vertebral arteries and their branches: the rostral spinal artery and the caudal inferior cerebellar artery. Anastomosis of the vertebral arteries gives rise to the basilar artery. This presented an anatomical variation with the formation of a double basilar artery, called the arterial island. Nine venous sinuses were observed in the dura mater: dorsal sagittal sinus, ventral sagittal sinus, transverse sinus, straight sinus, sigmoid sinus, temporal sinus, parietal sinus, basilar sinus and cavernous sinus, with morphological similarities in the origin, path and destination of the flow blood to the internal jugular vein, helping in the venous drainage function of the brain in this species. Of the venous sinuses observed, the cavernous sinus was of considerable clinical and surgical importance in Alouatta belzebul due to its topographic arrangement next to the internal carotid artery and pituitary gland, data similar to those described for Sapajus libidinosus, Macaca fascicularis, Macaca mulatta, Papio ursinus, Cercopithecus pygerithrus and Galago senegalensis. The morphological study of the telencephalon, as well as the mechanisms of lining, arterial irrigation and drainage of the venous sinuses, generated information about the brain organization of the primate Alouatta belzebul, which had not been previously described and many of these data generate subsidies for understanding other áreas ethological investigations.
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SABEC, D. K. Estudo macroscópico do telencéfalo, da vascularização da base e seios da dura-máter em Alouatta belzebul. 2020. 158 f. Tese (Doutorado em Ciência Animal) - Universidade Federal de Goiás, Goiânia, 2020.