2.2. Lineage tracing analysis

To verify the specific distribution of Prx1⁺ MSC on the periosteum of the femoral shaft with ageing, 1 week, 8 weeks, 12 and 24 months old mice (n = 3 per group) were killed, and the femurs were harvested for immunofluorescence analysis. To investigate the degree of Prx1⁺ MSC participating in bone regeneration in young and aged mice, 4 weeks and 12 months old Prx1CreER‐GFP;Rosa26^tdTomato mice (n = 3 per group) were received intraperitoneal injections of 75 mg/kg bodyweight tamoxifen (Sigma‐Aldrich) for 5 days before closed left femoral bone fracture was made. 20 At 2 weeks after surgery, the mice were killed, and the femurs were harvested for immunofluorescence.