Microvascular patterns of the dental pulp of the upper major incisor of the rabbit.

four regions or stages in the life cycle of the odontoblast. The pulpal arteries in the differentiating dental papilla cell region and the pre-odontoblastic region immediately spread into capillaries towards the odontoblastic layer. The capillaries formed a network in the shape of polygonal meshes. The capillary wall appeared to be continuous. In the young odontoblastic region, the capillaries undulated and built up a network which stood away from the arterioles, with smaller meshes. The continuous-type capillaries were altered to become fenestrated. The pulpal arteries in the old odontoblastic region formed the subodontoblastic plexus beneath the odontoblastic layer. Capillaries formed loops between the odontoblasts, and the tips of the loops extended to the terminal web. Fenestrations were very often observed near the tips of the loops. In the short odontoblastic region, the arteries directly altered to capillaries, which gave off lower loops at irregular intervals and again appeared to be continuous. Pulpal veins ran peripheral to the arteries anastomosing with one another towards the growing end, and confluenced into larger veins which were located in contact with the alveolar wall. The vascular patterns of the rabbit incisor pulp through the four regions in the life cycle of the odontoblasts apparently changed in proportion to the morphological changes of the odontoblasts through the .dentinogenesis.