Figure 2.

EGFP-Cre recombinase expression recapitulates endogenous Ascl3 expression. AIn situ hybridization on a paraffin section of submandibular gland from Ascl3^EGFP-Cre/+ female using a radioactively labeled antisense probe to Ascl3 coding sequence. Positive signal from endogenous Ascl3 mRNA expression (black grains) is concentrated in the ducts. Hematoxylin staining was used to stain all cells. Arrowheads indicate labeled duct structures. Ac, acinar cells; Du, duct cells. Scale bar is 50 µm.

B. Fluorescent image of a frozen section from Ascl3^EGFP-Cre/+ female submandibular gland. EGFP expression driven by the Ascl3 promoter is detectable in the nuclei of a subset of ductal cells (arrowheads). Ac, acinar cells; Du, duct cells. Scale bar is 100 µm.

C. Immunohistochemical staining of paraffin section from Ascl3^EGFP-Cre/+ submandibular gland examined using antibodies to Cre recombinase and aquaporin 5. Ascl3-expressing Cre+ cells are labeled red. Antibody to aquaporin 5 labels apical membranes of acinar cells and is shown in green. All nuclei are stained with ToPro3 (blue). Large round nuclei are acinar cells; smaller aligned nuclei are from duct cells. Arrowheads indicate duct cells in which Ascl3-driven Cre recombinase expression is detected. Ac, acinar cells; Du, duct cells. Scale bar is 50 µm.