An autoradiographic study of the in-vivo incorporation of [3H]-palmitic acid into the dentine and enamel lipids of rat incisors, with a comparison of rapid-freezing freeze-substitution fixation and aldehyde fixation.

Four and twenty-four hours after injection of the labelled precursor, there were twice as many silver grains scored with the cryotechniques as with conventional fixation. Absence of labelled-band formation in dentine, the diffusion of silver throughout the entire thickness of dentine as well as the layer of forming enamel. This suggests that lipids are membrane-associated components rather than true matrix-associated components.