Indirect visualization of ameloblast modulation in the rat incisor using calcium-binding compounds

Rats were injected with Calcein and killed 1 h, and 1, 2 and 3 days after injection. Incisors were stained with glyoxal-bis-(2-hydroxyanil) (GBHA) and the enamel surface examined in a fluorescence microscope with incident-light excitation. In maturing enamel Calcein produced five fluorescent double bands across the long axis of the tooth. GBHA produced a series of single red stripes, each of which was imposed on a double Calcein band 1 h after injection. At longer intervals after injection GBHA stripes were seen to be gradually displaced in the apical direction from the Calcein double bands. Since GBHA is known to stain enamel adjacent to smooth-ended ameloblasts this supports the view of a cyclic modulation of ameloblast morphology and function.