Double-labeled neurons in some regions of the brainstem after injections of FG and TMR-DA into the facial and hypoglossal nucleus, respectively, of the rats in the group 3.

In each rat, the numbers of FG-, TMR-single-labeled and FG/TMR-double-labeled neurons were counted in the pontomedullary reticular formation (RF), parabrachial nucleus (PBN) and the regions around the Vmo on both sides. And then, the ratio of FG/TMR-double-labeled neurons to total retrograde-labeled neurons (FG+TMR+FG/TMR) was calculated in each region. Cell counts were obtained from every fifth section of a series of serial sections of 30 µm thickness.