Improved preservation of intramitochondrial granules in rat-incisor odontoblasts by rapid-freezing and freeze-substitution fixation.

Odontoblasts fixed by rapid-freezing and freeze-substitution, compared to cells fixed with aldehyde, exhibited a larger number of microfilaments, a granular material inside the rough endoplasmic reticulum, many electron-dense aggregates in cytoplasmic vesicles and numerous intramitochondrial granules. Although these granules were located in odontoblasts facing a well-mineralized layer of dentine, this did not support the possible existence of a transfer pathway for intracellular calcium which plays some part in mineralization processes.