Ultrastructure of odontogenesis in the pike ( Esox lucius). Role of dental epithelium and formation of enameloid layer

Abstract

The role of the dental epithelial cells in the formation of teeth in the pike ( Esox lucius ) was investigated by electron microscopy. Initial dentine deposition, consisting primarily of bundles of coarse collagen bundles, formed under the influence of relatively undifferentiated dental epithelial cells similar to those related to initial dentine formation in developing mammalian and amphibian teeth. Following initial tooth dentine deposition, a calcifying granular enameloid layer, 0.5 μ m thick, formed on the tooth surface between the inner dental epithelial cells (IDE) and the dentine. The inner dental epithelial cells which produced the enameloid matrix showed ultrastructural features similar to secreting mammalian ameloblasts. The thin calcified surface enameloid layer in pike teeth is regarded to be similar to true ectodermal enamel. It lacked collagen, was produced by IDE cells (ameloblasts), and showed crystal arrangement perpendicular to the tooth surface. The differentiation of the outer dental epithelium, which occurred at the same time as enameloid deposition and tooth calcification, showed fine structure specialization for efficient transport of ions and water. An uncalcified cuticle, produced by the IDE, is deposited on the calcified tooth enamel surface.