(a) Masson’s trichrome–stained liver sections of mice at 6, 9, and 12 months of age showing the biliary abnormalities in various lines. Asterisks indicate dilated bile ducts, and arrows indicate bile duct proliferation. Bar = 200 μm. (b) Incidence of biliary dysgenesis per animal in each background at 3, 6, 9, and 12 months. There was no evidence of biliary dysgenesis in any background at 1 month. Liver dysgenesis at each time point and background was compared to corresponding B6 mice by using a 2-way analysis of variance followed by Dunnett’s multiple comparison test, but no statistical significance was evident. B6, C57BL/6J; BC, BalbC/cJ; 129, 129S6/SvEvTac. To optimize viewing of this image, please see the online version of this article at www.kidney-international.org.