Fig. 7. Confocal laser scanning images of killifish cystic fibrosis transmembrane conductance regulator (kfCFTR) immunofluorescence of mouse anti-human CFTR and goat anti-mouse IgG Oregon Green 488 in seawater-adapted killifish posterior intestine showing the distribution of kfCFTR (green fluorescence) in the enterocytes of an intestinal villus. (A) Red and green fluorescence overlaid. In approximately 80 % of sections, kfCFTR immunofluorescence is evenly distributed throughout enterocytes but is absent from goblet cells (asterisk) and present at low levels only over enterocyte nuclei (white arrow). Brush-border microvilli stain (non-specifically) with Mitotracker Red. (B) Same image as A but with bright field overlaid with green fluorescence. (C) In a minority (approximately 20 %) of sections, kfCFTR immunofluorescence was also present in the apical membrane (area between arrows). (D) Same image as C but with bright field overlaid with green fluorescence. Scale bars, 20 µm.