Mice

The P0-Cre, Wnt1-Cre and R26R transgenic mice were described previously (Danielian et al. 1998; Giovannini et al. 2000; Soriano 1999). Both P0-Cre and R26R reporter mice were maintained on the C57BL/6 background. Heterozygous P0-Cre male mice (P0-Cre/+) were mated with heterozygous R26R reporter female mice (R26R/+) to generate P0-Cre/+;R26R/+ mice. P0-Cre/+;R26R/R26R and R26R/R26R mice were generated by mating P0-Cre/+;R26R/+ mice with R26R/+ mice. P0-Cre/+;R26R/+ and P0-Cre/+;R26R/R26R mice were designated as P0-Cre;R26R mice. R26R/+ and R26R/R26R mice were designated as R26R mice (Control). Heterozygous Wnt1-Cre male mice (Wnt1-Cre/+) were mated with homozygous R26R reporter female mice (R26R/R26R) to generate Wnt1-Cre/+;R26R/+ (Wnt1-Cre;R26R) and R26R/+ (Control) mice. Experimental mice were housed under a standardized condition at the University of Michigan School of Dentistry and all handling protocols were approved by IACUC at University of Michigan. 2-month-old mice were euthanized by CO₂ asphyxia and 7-day-old mice were euthanized by decapitation. To detect the engineered Rosa26 locus and Cre transgene, PCR was performed using tail DNA as described previously (He et al. 2017; Liu et al. 2004; Soriano 1999).