Cell architecture in the papillary layer of rat incisor enamel organ at the stage of enamel maturation

This is the authors' abstract. We don't add key points for this paper.

Shape and arrangement of cells and extent of intercellular spaces were studied in sections of enamel organ cut in three planes: at right angles to the axis of the incisor tooth, at right angles to the axis of the ameloblasts, and parallel to the axes of the incisor and ameloblasts. The cells in contact with the base of the ameloblasts make up the proximal part of the papillary layer. They have a polygonal cross section close to the ameloblasts and point several sheet‐like cell processes towards the blood vessels which invaginate in the papillary layer. Intercellular spaces of constant width pervade the proximal part and provide a direct and straight communication between blood vessels and ameloblasts. The cells of the ridges make up the distal part of the papillary layer, and are flattened in the direction of the ridges. Intercellular spaces in the ridges are narrower than in the proximal part and visible with the light microscope only during a fraction of the enamel maturation period. No distinct cell layers are visible within the papillary layer during enamel maturation. All cells in the papillary layer may be in contact with the basement membrane investing the enamel organ. The structure of the papillary layer changes with the different phases of enamel maturation. Functional aspects of the papillary layer are briefly discussed.