Microvascular system of the rat incisor enamel organ. A scanning electron microscopic study of vascular corrosion casts.

The rat incisor is a commonly used model in studies of tooth eruption, amelogenesis and effects of mechanical loading on the dental and periodontal tissues. The purpose of this study was to assess the three-dimensional architecture of the microvascular bed of the rat incisor enamel organ, to describe the direction of blood flow, and to provide a histometric assessment of the vascular categories that can be statistically analyzed. Vascular corrosion casts were prepared and examined by scanning electron microscopy. The microvasculature of the labial periodontal space was arranged in three distinct layers. The inner layer in direct relation to the enamel organ consisted of a capillary network which was drained by short venules at the cemento-enamel junction. The intermediate layer consisted of arterioles oriented parallel to the long axis of the incisor mainly mid-labially, branching off smaller arterioles to the capillary network. The outer layer was formed by flattened sinusoid vessels of larger caliber. Blood supply was from the anterior superior alveolar artery branches through the arterioles into the capillary network. Drainage was postero-laterally along the cemento-enamel junction via short venules which emptied into the sinusoid vessels, finally to flow through Volkmann's canals into the alveolar bone via small venules. The findings demonstrate that the microvasculature of the rat incisor enamel organ has an exceptionally high level of physiologically-adapted structural organization.