Blood supply of the rat periodontal space during amelogenesis as studied by the injection replica SEM method.

Distribution of blood vessels at the labial periodontal space of the rat lower incisor teeth was studied, using Mercox-resin vascular casts, which were coated with gold-palladium and observed in a scanning electron microscope (SEM). Three different layers were identified in the vascular bed of the periodontium. In the inner layer the enamel organ was supplied by a blood capillary network that changed from a circular mesh to a ladder-like pattern during amelogenesis. The middle layer was supplied by small arteries and arterioles. Small arteries originated from the inferior alveolar artery; arterioles, arising from them, became blood capillaries. In the outer layer, the sinusoid veins continued with the blood capillaries which ran into the proximal and the distal sites of the inner layer. This venous layer is located near the alveolar bones. As capillary networks change in pattern during amelogenesis, the circular mesh is considered convenient to provide the required materials for the proliferation and differentiation of inner enamel epithelial cells as well as for early enamel matrix formation, whereas the ladder pattern seems suitable to supply numerous organic or inorganic materials for the advanced enamel matrix formation and calcification.