Fig. 5. Micrographs of the cell bodies of CI, CA1 and CA2 neurons stained by back-filling with Co²⁺ and Ni²⁺ ions. The schematic drawing (right) shows their locations in the CNS. The cell body of the CI neuron was located at a site near the midline on the side contralateral to the 10th nerve root containing the CI axon in the 1st segment. The cell bodies of the CA1 and CA2 neurons were located at sites, near the midline on the side ipsilateral tothe 3rd nerve root in the 3rd and 4th segments, respectively. Scale bar, 20 µm.