Chondrogenic potential of mouse calvarial mesenchyme.
Facial and calvarial bones form intramembranously without a cartilagenous model; however, cultured chick calvarial mesenchyme cells may differentiate into both osteoblasts and chondroblasts and, in rodents, small cartilages occasionally form at the sutures in vivo. Therefore, we wanted to investigate what factors regulate normal differentiation of calvarial mesenchymal cells directly into osteoblasts. In embryonic mouse heads and in cultured tissue explants, we analyzed the expression of selected transcription factors and extracellular matrix molecules associated with bone and cartilage development. Cartilage markers Sox9 and type II collagen were expressed in all craniofacial cartilages. In addition, Msx2 and type I collagen were expressed in sense capsule cartilages. We also observed that the undifferentiated calvarial mesenchyme and the osteogenic fronts in the jaw expressed Col2A1. Moreover, we found that cultured mouse calvarial mesenchyme could develop into cartilage. Of the 49 explants that contained mesenchyme, intramembranous ossification occurred in 35%. Only cartilage formed in 4%, and both cartilage and bone formed in 4%. Our study confirms that calvarial mesenchyme, which normally gives rise to intramembranous bone, also has chondrogenic potential.
Aberg
Thomas
T
Developmental Biology Programme, Institute of Biotechnology, PO Box 56, FIN-00014, University of Helsinki, Finland.
Rice
Ritva
R
Rice
David
D
Thesleff
Irma
I
Waltimo-Sirén
Janna
J
D000818:Animals; D002356:Cartilage / Q000166:cytology / Q000196:embryology; D002454:Cell Differentiation; D020219:Chondrogenesis; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D019899:Paracrine Communication; D012886:Skull / Q000166:cytology* / Q000196:embryology* / Q000378:metabolism; D046509:Tissue Culture Techniques; D014157:Transcription Factors / Q000096:biosynthesis
D016326:Extracellular Matrix Proteins; D014157:Transcription Factors