Extensive and coincident side branching of dentinal tubules.

Slices of decalcified cat's canine teeth were impregnated with silver nitrate. The stain was taken up by the dentinal tubules. In sections 100 microns thick cut parallel to the long axis of the tooth, dark staining lines were seen running at right angles to the dentinal tubules. Examination at higher power and in thinner sections showed this appearance to be due to the coincident side branching of dentinal tubules. The side branches anastomosed and formed a series of lateral channels in the dentine. These channels may allow for the lateral spread of dentinal caries and of stimuli applied to the peripheral dentine.