Banca de QUALIFICAÇÃO: NATACHA CINTIA FERREIRA FERNANDES

MORPHOLOGY OF THE HEART AND CARDIAC SKELETON OF Bradypus variegatus AND Tamandua tetradactyla

fibrous trigones, fibrocartilage, common sloth.

All members of the superorder Xenarthra share a distinctive feature: the presence of supplementary paired intervertebral joints in the lumbar vertebrae, known as the xenarthral process. The lesser anteater, or Tamandua tetradactyla, is found in several countries in South America, with records throughout Brazil. Classified as Least Concern by the International Union for Conservation of Nature, it has an elongated nose and tongue, absence of teeth, short and dense fur with golden color on the back and black bands on the abdomen. While Bradypus variegatus also known as the three-toed sloth is found in the tropical forests of the New World, mainly in South America. Despite being classified as Least Concern, it faces challenges due to habitat degradation and fragmentation, especially in Brazil. Sloths, including the species in question, have peculiar physiological characteristics, such as low body temperature and slow metabolism. Its heart is adapted to its slow lifestyle, being compatible with that of other mammals in terms of structure and division into chambers. Furthermore, the cardiac skeleton is a structure that provides support to the heart and electrical isolation between atria and ventricles. With the aim of microscopically studying the tissues that make up the cardiac skeleton and that support the heart of Bradypus variegatus, four adult specimens from the Bosque Rodrigues Alves Jardim Zoobotânico da Amazônia were analyzed. The hearts were fixed in formaldehyde solution and processed histologically, using stains such as Hematoxylin and Eosin and Trichomic Gomori. The partial results revealed that the heart of the three-toed sloth is made up of four cardiac chambers, being small and round, like that of other mammals. As for microscopy, the cardiac skeleton (fibrous trigones) in this species is formed by fibrocartilage, with collagen fibers in the matrix and chondrocyte cells randomly distributed throughout the tissue.