Fig. 9. A model of paracrine and autocrine EDN1 signaling in the fish gill. The diagram shows a lamellar cross-section (see Figs 5, 6, 7) with pillar cells (PCs) in gray, pavement cells (PVCs) and a lamellar arteriole (LA) adjacent to the interlamellar region of the gill containing mitochondrion rich-cells (MRCs), a neuroendocrine cell (NEC), and the gill vasculature. Cyclo-oxygenase-2 (COX-2) and neuronal nitric oxide were previously immunolocalized in the killifish gill (Choe et al., 2006; Hyndman et al., 2006). NKA and the cystic fibrosis transmembrane conductance regulator (CFTR) are used as markers for the MRC (Katoh et al., 2001). See text for details.