Fig. 4. (A) Orthodromically conducted impulses were recorded at the proximal cut-stump of the CI, CA1 and CA2 nerves on the heart (orth). The impulses were induced by stimulation of the nerve roots at the distal cut stumps of the 10th, 16th and 19th roots of the SEG, respectively. The sites of recording and stimulation of antidromically conducted impulses (ant) were contrary to those of orth. Five traces were superimposed in each recording. The diagrams below show stimulation and recording on the cutting sites for CI, CA1 and CA2 (arrows) and 10th, 16th and 19th nerve roots (NR; arrowheads). The right and left sides of the SEG are reversed. (B) Micrographs of resin cross sections of the CI, CA1 and CA2 nerves. A single axon (a) is seen in each section. Scale bar, 10 µm.