Figure 1. eGFP expressing cells are strongly immunopositive for CCK.

Representive images of transverse sections of duodenum from CCK-eGFP mice. A: eGFP-tagged cells (green) were flask-shaped with a diffuse distribution, characteristic of ‘open-type’ enteroendocrine cell. B: Immunostaining with anti-CCK antibody (red) showed colocalization of CCK and eGFP in ∼ 90% of eGFP-labelled cells. C: High magnification micrograph (2.5X digital zoom) revealed I-cells had a narrow apical membrane (arrow) that was in contact with gut lumen and a broad basolateral membrane (asterisk) with adjacent strong CCK staining. In all images, nuclei were counter-stained with Hoechst 33342 (blue).