Ultrastructural quantification of collagen in the articular disc of the temporomandibular joint of the rabbit.

Collagen fibril diameters were quantified in two regions of the articular disc of this joint. One region was the thinner, translucent central part of the disc; the other was from the thicker, opaque peripheral part more anteriorly. Mean collagen fibril diameters in the thicker zone were small and had a unimodal distribution. In contrast, mean collagen fibril diameters in the thinner central region were larger and with a much wider range of values, as indicated by the larger standard deviations. It was concluded that regional variations exist in the collagen of the rabbit articular disc and may reflect the mechanical loads to which the disc is subjected.