Fig. 1. Identification and localisation of chromaffin cells within the posterior cardinal vein (PCV) tissue of rainbow trout based on the double labelling of (A) nucleic acids and (B) catecholamines or the double labelling of (D) dopamine ß-hydroxylase (DßH) and (E) catecholamines. Panel C is an overlay image of the sections shown in A and B (nucleic acids and catecholamines appear in red and green/yellow, respectively). Panel F is an overlay image of the sections shown in D and E (DßH and catecholamines appear in red and green, respectively; yellow indicates co-localisation of catecholamines and DßH). Note that the labelling patterns for DßH and catecholamines are identical. Scale bars D–F, 100 µm; scale bars A–C, 50 µm.