EARLY INNERVATION OF DEVELOPING DECIDUOUS TEETH

Abstract

The difficulty in staining terminal nerve fibers led to confusion as to when a developing tooth first received a nerve supply. Serial sections of human embryos stained with Ag were studied. Fibers of the trigeminal nerve grew into the maxillary and mandibular processes before there were signs of tooth development. Early in development alveolar nerves formed plexuses related to the dental laminae before tooth buds formed. Alveolar branches related to the rostral portions of the dental laminae developed earlier than those related to areas where molar tooth buds will develop. As the enamel organ developed the adjacent mesenchyme condensed to form a ball of cells which contributed to the formation of the dental papilla. At an early age nerves were followed into this mesenchymal ball where they were lost. There was an early innervation of the developing tooth. The main branches of the alveolar nerves were demonstrated in the 6th wk of development. One embryonic tissue may have an inductive influence on another developing tissue. Nerve fibers growing into mesenchyme adjacent to the oral epithelium may have a causative effect on developmental processes. Developing taste buds were dependent on the inducing influence of nerves and the developing tooth bud may have a similar dependence.