Figure 1.

Illustrations of the mechanisms of CreER recombination and of common bile duct injection. (A) The elastase or Sox9 promoter located upstream of the CreER gene allows specific CreER expression in acinar or ductal cells, respectively. The presence of TAM induces Cre-mediated recombination, through its specific interaction with the ligand binding domain of the estrogen receptor (ER) coupled to the Cre. Activated CreER deletes the stop cassette inserted between the two loxP sites in the ROSA26 locus, upstream of the gene coding for YFP, via homologous recombination. Thus, YFP is specifically expressed in acinar or ductal cells. (B) After dissection, mouse's head should be placed face up the experimenter. Using two straight forceps flip the liver lobes so that the common bile duct becomes visible, from the liver to the duodenum. Clamp the intersection point of the duct with the duodenum (Ampulla of Vater). Then, delicately insert a curved needle (30 gauge) in the duct and inject 3-to-5 mL of cold Col-EGTA solution. The pancreas will blow and take a white appearance. The detailed technical procedure is provided in the text.