(a-c) Aggrecan IHC combined with cell lineage tracing (Acan-CreERT2 was activated at P3, tracing the fate of chondrocytes) demonstrated highly expansion of Aggrecan+ cartilage area in KO condyles at ages of postnatal 10-days (a, right panels), 3-weeks (b, right panels), and 7-weeks (c, right panels), supporting the notion that there is a great increase in chondrogenesis in Dmp1 KO condyles.