DISTRIBUTION OF DORSAL ROOT FIBERS IN CAT . AN EXPERIMENTAL STUDY WITH NAUTA METHOD

The distribution of degenerating fibers following single section of every cervical dorsal root (DR) and DRs T4, T8 and L4 was observed with the aid of the Nauta method. The following results were obtained. 1. (1) The intimate overlap between distribution areas of two adjacent cervical dorsal roots in the nucleus proprius of the posterior horn prevented their topographical separation. The distribution of degenerating fibers of every second cervical dorsal root, however, showed much less overlapping (Fig. 2). 2. (2) Termination of DR C2 fibers was found in the interpolar nucleus of the spinal trigeminal nucleus (Fig. 3). 3. (3) The dorsal commissural nucleus in the cervical cord received fibers from DRs C7 and C8 (Figs. 1b and 4). 4. (4) The dorsal root fibers displayed preterminal fibers in the intermedio-medial zone. They were divided into two groups, the dorsolateral and ventromedial plexuses. (a) The former was unique to the dorsal roots of the intumescentiae, whereas the latter was commonly found for all dorsal roots examined. (b) Both plexuses extended above and below the rhizotomized segment as shown in Table I. (c) The dorsolateral plexus showed a close topographical relation to the thoracic nucleus (Fig. 7). © 1969.