Chondrocytes Directly Transform into Bone Cells in Mandibular Condyle Growth

Journal article

Publication Details

Author(s): Jing Y, Zhou X, Han X, Jing J, Mark K, Wang J, De Crombrugghe B, Hinton RJ, Feng JQ
Journal: Journal of Dental Research
Publication year: 2015
Volume: 94
Journal issue: 12
Pages range: 1668-75
ISSN: 0022-0345


For decades, it has been widely accepted that hypertrophic chondrocytes undergo apoptosis prior to endochondral bone formation. However, very recent studies in long bone suggest that chondrocytes can directly transform into bone cells. Our initial in vivo characterization of condylar hypertrophic chondrocytes revealed modest numbers of apoptotic cells but high levels of antiapoptotic Bcl-2 expression, some dividing cells, and clear alkaline phosphatase activity (early bone marker). Ex vivo culture of newborn condylar cartilage on a chick chorioallantoic membrane showed that after 5 d the cells on the periphery of the explants had begun to express Col1 (bone marker). The cartilage-specific cell lineage-tracing approach in triple mice containing Rosa 26(tdTomato) (tracing marker), 2.3 Col1(GFP) (bone cell marker), and aggrecan Cre(ERT2) (onetime tamoxifen induced) or Col10-Cre (activated from E14.5 throughout adult stage) demonstrated the direct transformation of chondrocytes into bone cells in vivo. This transformation was initiated at the inferior portion of the condylar cartilage, in contrast to the initial ossification site in long bone, which is in the center. Quantitative data from the Col10-Cre compound mice showed that hypertrophic chondrocytes contributed to ~80% of bone cells in subchondral bone, ~70% in a somewhat more inferior region, and ~40% in the most inferior part of the condylar neck (n = 4, P < 0.01 for differences among regions). This multipronged approach clearly demonstrates that a majority of chondrocytes in the fibrocartilaginous condylar cartilage, similar to hyaline cartilage in long bones, directly transform into bone cells during endochondral bone formation. Moreover, ossification is initiated from the inferior portion of mandibular condylar cartilage with expansion in one direction.

FAU Authors / FAU Editors

von der Mark, Klaus Prof. Dr.
Medizinische Fakultät

Additional Organisation
Lehrstuhl für Experimentelle Medizin mit dem Schwerpunkt Molekulare Pathogeneseforschung

External institutions with authors

Sichuan University (SCU) / 四川大学
Texas A&M University Health Science Center (TAMHSC)
University of Texas MD Anderson Cancer Center

How to cite

Jing, Y., Zhou, X., Han, X., Jing, J., Mark, K., Wang, J.,... Feng, J.Q. (2015). Chondrocytes Directly Transform into Bone Cells in Mandibular Condyle Growth. Journal of Dental Research, 94(12), 1668-75.

Jing, Y., et al. "Chondrocytes Directly Transform into Bone Cells in Mandibular Condyle Growth." Journal of Dental Research 94.12 (2015): 1668-75.


Last updated on 2018-06-10 at 02:49