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Highlights • A single intra-articular injection of CFA was efficient to induce a persistent inflammatory process in the ipsilateral TMJ. • The articular inflammation reduced area and diameter of fibers of masticatory muscles. • Induced inflammation in TMJ caused morphological and molecular changes in the contralateral joint. Abstract Objective To investigate morphological and biochemical changes in an experimental model of temporomandibular joint (TMJ) arthritis, as well as examine contralateral joint involvement and morphometric aspects of masticatory muscles in affected animals. Design Forty Wistar rats were allocated into three groups, as follows: a healthy control group (HG); and a group with arthritis induced in the left TMJ (IG); and a contralateral group with noninflamed right TMJ (CG). Arthritis was induced by intra-articular injection of 50 μL of Complete Freund's Adjuvant (CFA). Morphological analysis was performed using histological sections of TMJs stained with hematoxylin-eosin, picrosirius and toluidine blue. In addition, histomorphometric analyses of the articular cartilage, articular disc and masticatory muscles, were performed. Biochemical analysis of TMJ tissues included dosage of sulfated glycosaminoglycans (GAGs), zymography of the Matrix Metalloproteinases (MMPs) 2 and 9 and ELISA for the cytokines IL-6, TNF-α and IL-1β. The data were analyzed by paired and unpaired t-tests, with a p < 0.05. Results IG animals presented morphological and biochemical changes in their TMJ, including synovial membrane hyperplasia; chronic inflammatory infiltrate; collagen fiber disorganization in the disc; reduced proteoglycans in the cartilage; greater disc thickness; lower cartilage thickness; lower feed intake; higher activity of MMP-9 and MMP-2, and higher concentration of IL-6, TNF-α, and IL-1β, as compared to HG. CG animals showed posterior disc thickening; reduced proteoglycans in the cartilage; lower collagen fiber organization of the disc; active MMP-9, and higher concentration of IL-6 and TNF-α compared to HG animals. Articular inflammation reduced the area and diameter of fibers of the temporal (right), medial pterygoid (left), and lateral pterygoid (right and left) muscles as compared to HG animals. Conclusion TMJ arthritis reduced the area and diameter of masticatory muscle fibers and caused morphological and molecular changes in the contralateral joint. [ABSTRACT FROM AUTHOR]

High molecular weight hyaluronic acid (HMWHA) has been used to treat temporomandibular joint (TMJ) disorders, but controversial results have been described. This study aimed to characterize the morphological and biochemical actions of HMWHA on induced arthritis of the TMJ. Twenty-four male Wistar rats were used, and arthritis of the TMJ was induced through an intra-articular injection of Complete Freund's Adjuvant (CFA) (50 μl). One week after arthritis induction, the animals were treated with HMWHA (once per week for three weeks). Histological analyses were performed using sections stained with hematoxylin-eosin, toluidine blue and Picrosirius. Were also performed histomorphometric analysis and birefringence of collagenous fibers (polarization microscopy). Biochemical analyses of TMJ tissues were carried out through measurements of sulfated glycosaminoglycans and zymography for evaluation of metalloproteinase-2 and -9 (MMP-2 and -9). Data were analyzed using paired t -test and unpaired t -test, with a 5% significance level. HMWHA reduced histologic changes and thickness of the articular disc, led to a greater arrangement of collagenous fibers, lower concentration of sulfated glycosaminoglycans and lower activity in all isoforms of MMP-2 and -9 in TMJs with induced arthritis. These findings suggest that HMWHA may exert a protective effect on the TMJ. [ABSTRACT FROM AUTHOR]

COVID-19 is an infection caused by the SARS-CoV-2 virus, initially identified in the city of Wuhan, China, in December 2019. Since then, the virus has spread to the continents, causing a major pandemic. The impacts of this pandemic on the education of human anatomy interfere in at least two aspects: (1) receiving and managing anatomical specimens in anatomy laboratories and (2) adaptations for classes on remote virtual teaching. Therefore, this study reviewed and discussed the legal and bioethical aspects, considering the scenario of a South American Country, aiming to stimulate the debate on these two relevant themes in the international community. Because of the COVID-19 pandemic and the impossibility of mass testing, anatomists and other workers in the field must deal with the risk of receiving bodies infected with SARS-CoV-2. In this situation, additional care measures in biosafety practices are essential to protect the staff. Such measures are: the bodies must be preserved by the perfusion of formaldehyde or other fixative solutions; embalming must be performed in ventilated rooms with a good air exhaust system; to avoid excessive manipulation of bodies and procedures such as pulmonary insufflation or craniotomy; and proper use of personal protective equipment, including lab coat, gloves and masks. As for exposure of body images in online classes, this review showed that there are no legal impediments to this end. However, anatomists must adopt measures aimed at protecting the memory of the deceased, such as using secure digital platforms with restricted access; family authorization/consent and student awareness. [ABSTRACT FROM AUTHOR]