The relationship of proteoglycans to developing transalveolar fibres in the alveolar bone of the mouse.

Proteoglycans are of interest because of their complex role in the development and maintenance of connective tissues. The present study demonstrates changes in the distribution of proteoglycans in the developing alveolar bone of the mouse using techniques of light and high-voltage electron microscopy. In early development proteoglycans are uniformly distributed throughout the interdental septum. By day 25 there is a loss of proteoglycans, probably as a result of mineralization and the maturation of the collagen of transalveolar fibres. By day 45 proteoglycans are distributed only in tissues adjacent to transalveolar fibres. These proteoglycans occupy the channels surrounding transalveolar fibres and the adjacent bone matrix. It is proposed by the authors that these proteoglycans are involved in the maintenance of the collagen of the transalveolar fibres. Because of the absence of fibroblasts adjacent to transalveolar fibres, proteoglycans are thought to be essential carriers of tropocollagen to these large fibres.