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Apoptosis in murine calvarial bone and suture development
Author(s) -
Rice David P. C.,
Kim HyunJung,
Thesleff Irma
Publication year - 1999
Publication title -
european journal of oral sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 93
eISSN - 1600-0722
pISSN - 0909-8836
DOI - 10.1046/j.0909-8836.1999.eos107406.x
Subject(s) - mesenchyme , tunel assay , calvaria , fibrous joint , mesenchymal stem cell , microbiology and biotechnology , terminal deoxynucleotidyl transferase , anatomy , frontal bone , craniofacial , apoptosis , pathology , chemistry , biology , medicine , skull , biochemistry , genetics , in vitro
To study the possible role of apoptosis in calvarial bone and suture development, terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) was performed on whole mount and sectioned calvariae from mice aged between E14 and P6. We also analyzed by in situ hybridization the expression of Msx2, Bmp4 and Bmp7 genes, which are known to act in conserved signaling pathways leading to apoptosis. We found TUNEL-positive cells from E16 onwards in the calvarial bones, intervening sutures and fontanelles. TUNEL-positive osteoblasts and preosteoblasts were identified at or close to the osteogenic fronts, areas of intense osteogenic activity, with TUNEL-positive mesenchymal cells located in the midsutural mesenchyme. TUNEL-positive osteoclasts and osteocytes were also observed in a sporadic fashion, as well as TUNEL-positive dural cells. Msx2 was expressed in the sutural mesenchyme and the dura mater. Bmp4 was expressed in the developing bone, underlying dura mater, the osteogenic fronts, and also weakly in the sutural mesenchyme. Bmp7 was detected at the same locations as Bmp4 but with noticeably stronger intensity in the meninges and overlying epidermis. We propose that this apoptosis is part of normal suture development, and is integral to the balance between bone formation and resorption, so that abnormal apoptosis may lead to premature (Craniosynostosis) or delayed (Cleidocranial dysplasia) suture closure.