Immunohistological analysis of CftrTgH(neoim)HguCftr expression. Immunocytochemical staining of Cftr in the duodenum, jejunum, ileum of wild type mice MF1 (A, B, C), duodenum (E, magnification ×200), jejunum (F, magnification ×200) and ileum (G, magnification ×400) of homozygous F28 CF/1-CftrTgH(neoim)Hguand duodenum (H, magnification ×200), jejunum (I, magnification ×200) and ileum (J, magnification ×400) of F27 CF/3-CftrTgH(neoim)Hgumice was performed with the R3195 anti-Cftr antibody as described in Methods. Wild type mice showed intense Cftr staining of the apical border of epithelial cells. In CF/1-CftrTgH(neoim)Hguand CF/3-CftrTgH(neoim)Hgumutant mice Cftr staining was weaker and more diffuse mainly in the upper villus region. Ileum of a CF-Knock out mouse (D) was used as negative control.