Osteogenic fate of hypertrophic chondrocytes

Endochondral bone formation is largely dependent on cartilage lineage cells. The chondrocytes in growth plates continuously undergo a sequential process from prolif-eration to terminal hypertrophic differentiation [1]. Once differentiated, hypertrophic chondrocytes elicit multiple functions such as determining bone length, inducing os-teogenesis as well as directing bone mineralization, and eventually disappear at the chondro-osseous junction. The fate of the terminally differentiated hypertrophic chondrocytes is conceptually important for understand-ing its role in endochondral bone formation. It has been debated for decades whether the terminally differentiated hypertrophic chondrocytes die by apoptosis or undergo osteogenic transdifferentiation, however, clear in vivo evidence is lacking [2]. Here, through lineage tracing, w