Microanatomy of the moose temporomandibular joint (Alces alces; Linnaeus, 1758)

Temporomandibular joint (TMJ) histology was investigated in 8 female Scandinavian moose. 5 were 1-year-old with a carcass weight (cw) of 125-140 kg, and 3 were 2-years-old (160-175 kg cw). The condylar articular surface consisted of a connective tissue lining with parallel collagen fibres. Numerous blood vessels were observed adjacent to the joint chamber. Below the fibrous layer, a proliferative cellular zone of undifferentiated mesenchymal cells was situated. These cells differentiated into chondroblasts and hypertrophied chondrocytes. Further down, an endochondral ossification process was initiated. Vertically directed invaginations were observed. A similar cellular organization was identified in the temporal component. However, the undifferentiated mesenchymal cell layer was discontinuous. The disc showed dense collagen bundles without main alignment. Vessels were identified throughout the entire disc. The results indicate that the cellular organization of the moose TMJ is similar to the TMJ histology found in other mammals but differences do occur.