pERK-LI cells in the bilateral medulla and upper cervical cord following pulpal administration of PBS or α, β-meATP. A: Camera-lucida drawings of pERK-LI cells in the ipsilateral (ipsi) and contralateral (cont) medulla and upper cervical cord following pulpal administration of PBS or α,β-meATP (100 mM). Vc; trigeminal spinal subnucleus caudalis. NTS; nucleus tractus solitarii. CVR; caudal ventral reticular nucleus. Ba: Photomicrograph of pERK-LI cells in Vc. Bb: NeuN-Li cells (red) in Vc, Bc: pERK-Li cells (green) in Vc, Bd: Double labeling of pERK (green) and NeuN (red) in Vc. Arrows indicate both NeuN and pERK double-labeled cells in Vc.