The pyroantimonate reaction and transcellular transport of calcium in rat molar enamel organs.

The distribution of calcium in the cells of the enamel organ of developing rat molar tooth germs was studied by the pyroantimonate method. It was found that there was a specific localization to the inner leaflet of the plasma membrane of both secretory and maturation phase ameloblasts. This information can be used to support the model for transcellular transport of calcium involving membrane fluidity, with phosphatidylserine as a carrier (Reith 1983). It can also support an alternative model involving movement of calcium ions over a surface of acidic phospholipids on the inner leaflet of the plasma membrane, without involving the necessity for membrane fluidity.