Comparison between human and rat TMJ: anatomic and histopathologic features

Abstract

Purpose: To describe and evaluate normal rat temporomandibular joints from anatomic and histopathologic point of view and make a comparison between this joint in rats and humans. Methods: Twelve male adult Wistar rats (12 same side joints) were used in this procedure. The following anatomical structures were histologically evaluated in a qualitative fashion: condyle, disc, temporal bone, retrodiscal tissue and synovia. The macroscopical and microscopic study of the human TMJ was based on the current literature. Results: The TMJ is surrounded by a thin capsule, consisting of fibrous tissue, and a synovial lining. The mandibular angle has a prominent shape. The glenoid fossa is flat, with no eminences. Histologically, the TMJ is composed of different tissues that comprise the mandibular head, mandibular fossa and fibrocartilaginous disc. A layer of hyaline cartilage covers the articulating cortical condyle and temporal bone. Conclusion: Morphologically and histologically, the articular structure of rats is, on the whole, similar to that of humans. In these animals there is no articular eminence. Key words: Temporomandibular Joint. Anatomy, Comparative. Animal Experimentation. Rats. RESUMOObjetivo: Descrever e avaliar a articulação temporomandibular de ratos sob o aspecto anatômico e histológico e realizar uma comparação entre esta articulação e a de humanos. Métodos: Foram utilizados doze ratos adultos Wistar (12 articulações do mesmo lado). As seguintes estruturas anatômicas foram avaliadas de forma qualitativa: côndilo, disco, osso temporal, tecido retrodiscal e sinóvia. O estudo macroscópico e o microscópico da ATM humana foram baseados na literatura atual. Resultados: A ATM é envolvida por uma fina cápsula, formada por tecido fibroso e cobertura sinovial. O ângulo mandibular é proeminente. A fossa glenoide é rasa, sem eminência articular. De acordo com os achados histológicos, a ATM é composta por diferentes tecidos, são eles a cabeça da mandíbula, a fossa mandibular e o disco fibrocartilaginoso. Uma camada de cartilagem hialina recobre a superfície articular do côndilo e do osso temporal. Conclusão: De acordo com os achados morfométricos e histológicos, a estrutura articular em ratos é, no geral, similar a articulação humana. Exceto que nesses animais não há eminência articular.

A Comparative Study of the Dentition and Temporomandibular Joint Anatomy and Histology Adult Dogs

“…The temporomandibular joint is a group of anatomic structures that, with a special group of muscles, is responsible for the movement of the mandible during mastication [15]. It is classified as a hinge-sliding joint; it has a unique structure and function.…”

Functional adaptability of temporomandibular joint mechanoreceptors after an increase in the occlusal vertical dimension in rats

“…Neural signals of somatic sensations begin with the excitation of mechanoreceptors in the sensory nerve, and the excitation of mechanoreceptors is accomplished by the opening or closing of ion channels. 23 Therefore, we speculate that iOVD induces temporary degeneration of TMJ mechanoreceptors, which finally adapts. Moreover, the insignificant temporal change in the average firing frequency between both groups may indicate the final functional adaptation.…”

Development of temporomandibular joint ankylosis in rats using stem cells and bone graft

“…Rats are easy to acquire and inexpensive to keep because of their small size. Their TMJ is much smaller than the human one, and there is no articular eminence in the rat TMJ, but morphologically and histologically, the articular structure of rats is, on the whole, similar to that of humans 18 . The absence of the articular eminence may make the movement of the mandible highly specialized for extensive protrusive movements 18 .…”

“…Their TMJ is much smaller than the human one, and there is no articular eminence in the rat TMJ, but morphologically and histologically, the articular structure of rats is, on the whole, similar to that of humans 18 . The absence of the articular eminence may make the movement of the mandible highly specialized for extensive protrusive movements 18 . Even though the results of this study cannot be extrapolated to humans because of species differences, they could give rise to a new treatment approach.…”