D shows a highly effective injection site in a Neutral Red-stained section (arrow; the site is also marked as `1' in B). Pontamine Sky Blue staining became faint after tissue processing.
Abbreviations: Aq, aqueduct; Cereb., cerebellum; DTgP, dorsal tegmental nucleus; IC, inferior colliculus; lfp, longitudinal fasciculus of the pons; LPB, lateral parabrachial nuclei; MnR, median raphe nucleus; PAG, periaqueductal grey; PnC, pontine reticular nucleus, caudal part; PnO, pontine reticular nucleus, oral part; scp, superior cerebellar peduncle; and 4V, fourth ventricle.