Ultrastructure of inter-odontoblastic fibres in the rat molar.

Radially directed inter-odontoblastic collagen fibres were observed in ultra-thin sections of the radicular pulp/predentine complex of rat molars. Bundles of fibres crossed the distal junctional complexes of the odontoblasts, went through the whole thickness of the predentine and were incorporated into the mineralized dentine. Scanning electron microscopy showed that bundles of radial fibres are not found between the coronal odontoblasts of the rat molar but only in the root. The radial fibres were inserted into the predentine along vertical long-axial crests. The intercrest interval was not tightly fixed and the pattern of fibre-bundle insertion did not show a regular periodicity.