Figure 4

Immunohistochemical localization of the AQP6 protein in the rat stomach, jejunum and proximal colon. In the stomach, intense AQP6 staining was observed in the isthmus and neck cells, a lower signal in chief cells and in some parietal cells (b, inset). AQP6 immunoreactivity appeared to be confined to intracellular structures. In jejunum, labelling was present in the upper part of the villus and reduced or absent in the crypt (d). Intense AQP6 immunoreactivity was observed in the apical part of the epithelial cells (d, inset). In the proximal (f) part of the colon labelling was present in the surface epithelial cells of the crypt and almost absent in the epithelium at the base of the crypt. Intense AQP6 immunoreactivity was observed in the apical part of the epithelial cells (f, inset). Goblet cells were not stained. In the kidney, AQP6 immunoreactivity was observed in the intercalated cells of the collecting duct (h). Controls were negative (a, c, e, g). Bars correspond to 100 μm. Bars in kidney sections correspond to 50 μm.