INTRODUCTION
In vertebrates, the skeleton is formed through intramembranous and endochondral ossification.1–2 The former forms the skull vault and part of the clavicle directly through condensation and differentiation of mesenchymal stem cells (MSCs) into osteopro-genitors, osteoblasts, and, terminally, osteocytes, while the latter forms the majority of skeletal elements, including all long bones and vertebrae.