Distinctive autoradiographic patterns of glycine incorporation in rat enamel and dentine matrices

Abstract

Localization of glycine-H 3 in dentine and enamel matrices of growing rat molars has been investigated autoradiographically. The label is first localized in odontoblasts and ameloblasts, reflecting intracellular synthesis of the respective matrix proteins, but is rapidly transferred to the adjacent matrices. In dentine matrix, the labelled material appears as a discrete, intensely reactive band, which does not decrease in intensity with time. Dentine matrix present prior to the time of glycine-H 3 administration does not become labelled. Although labelled enamel matrix also appears initially as a reaction band, it soon spreads through the thickness of the matrix layer, including that which was present prior to the time of treatment. The mechanism by which this redistribution of enamel matrix protein occurs is not known. The resulting diffuse reaction in enamel matrix is maintained during the time when definitive enamel mineralization begins, i.e. at the same time that an absolute reduction in the mass of enamel matrix is assumed to occur. These findings are discussed in terms of their chemical and physiological implications.