OBJECTIVETo study the distribution character of the trigeminal sensory afferent fibers in rat's trigeminal sensory root (RxV) and to explore the possibility of selectively injury of the pain afferent fibers.

METHODSThe retrograde tracer fluorogold (FG) was injected into trigeminal spinal subnucleus and pontine nucleus respectively. After 7 days survival, the rats were sacrificed and the RxV was removed and sectioned. The distribution of FG at RxV was studied under fluorescent microscope and its character was analyzed.

RESULTSAfter being introduced into trigeminal spinal rostral nucleus, the FG could be observed at the lateral portion on the sections of RxV. The fibers were small and concentrated. The interpolaris subnucleus and caudal subnucleus injection group also showed small and concentrated fibers in the lateral portion of RxV, but the distribution area was larger than that of the rostral subnucleus group. While being injected into trigeminal pontine nucleus, the FG positive axons could be found in the ventral, medial and central portion of the RxV cross sections. These fibers were thicker and more scattered compared to those projecting into trigeminal spinal nucleus.

CONCLUSIONThe fibers relating to transporting pain sensory concentrate at a certain area of rat' s RxV, which indicate that selectively injury of the pain afferent fibers of RxV should be possible.