ESPE Abstracts

Epiphyseal growth plates, tiny cartilage discs located to the end of long bones, are necessary for longitudinal growth of the skeleton. When and why these structures appeared as individual organs was not very clear until recently. Bringing together an evolutionary approach with comparative analysis, mathematical modelling and both physical and biological experiments allowed to reveal that spatial allocation of the growth plate reduces mechanical stresses within the structure, which are otherwise harmful for hypertrophic chondrocytes. This mechanical protection is executed by bony epiphyses, which separates the growth plate from articular cartilage. This protection comes at the expense of numerous chondro-progenitors. Analysis of clonal dynamics revealed that bony epiphysis creates a stem cell niche within the underlying growth plate, allowing the remaining chondro-progenitors to acquire stem cell properties and maintain longitudinal growth. Taken together, these observations revealed novel principles underlying linear skeletal growth.