True enamel matrix of the newt, Triturus pyrrhogaster, contains no sulfated glycoconjugates

Abstract

The ultrastructural distibution and histochemical properties of sulfated glycoconjugates were investigated in the developing enamel of the adult newt, Triturus pyrrhogaster, by use of the high-iron diamine thiocarbohydrazide silver proteinate (HID-TCH-SP) staining and enzymatic digestion methods. Development and ultrastructure of the enamel were also studied. After deposition of the mantle dentin matrix to a certain thickness, the first enamel matrix, globular in shape, appeared in juxtaposition to the dental basement membrane and tended to be intermixed with the previously deposited dentin matrix. Subsequently, enamel matrix was deposited outside (ameloblastic side) of the dental basal lamina and formed a true enamel layer. Thus, developing enamel of the newt consists of two layers: (1) an inner layer made up of a dentin-enamel mixed matrix and (2) an outer layer composed of only true enamel matrix. HID-TCH-SP precipitates resulting from the abovementioned studies were found in the mixed matrix and were identified as chondroitin sulfates; in contrast, the true enamel matrix contained no sulfated glycoconjugates.