Responses of pulpal tissues were assessed histologically in teeth that had been transplanted after root formation was moderately well advanced. Degeneration occurred in the coronal third, but the area was repopulated by cells proliferating from the center of the pulp. Apically, the tissues, including the odontoblasts, remained vital and functional. Widespread intrapulpal formation of osteodentin was prominent in later observation periods. Apical closure occurred prematurely by production of osteodentin and cellular cementum in the form of an apical diaphragm; these mineralized tissues were confluent with a similarly active deposition of cellular cementum apically on the root surface.