Representation of upper and lower primary teeth in the trigeminal sensory nuclear complex in the young dog

Transganglionic transport of horseradish peroxidase-wheat germ agglutinin conjugate entrapped in polyacrylamide gel was used to study the patterns of termination of primary afferents that innervate the upper and lower primary tooth pulps within the trigeminal sensory nuclear complex of the young dog. The lower and upper primary tooth pulp afferents projected to the subnucleus dorsalis of the principal nucleus, the rostrodorsomedial part and subnucleus dorsomedialis (Vo.dm) of the pars oralis, the nucleus of the intermediate plexus (Vi.ip) of the pars interpolaris, and laminae I, II and V of the caudalis. The lower and upper primary teeth were topographically represented in the Vo.dm, rostrocaudal mid-levels of Vi.ip, and in laminae I/V of the caudal levels of the pars caudalis, whereas an extensive overlapped projection was seen in other subdivisions.