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. Author manuscript; available in PMC: 2011 Nov 15.
Published in final edited form as: Dev Biol. 2010 Aug 19;347(2):258–270. doi: 10.1016/j.ydbio.2010.08.010

Fig. 2. Conditional inactivation of Jagged1 in mesoderm and not in neural crest results in craniosynostosis and defects in the boundary between the coronal suture and prospective frontal and parietal bones.

Fig. 2

(A-C) The R26R allele served as an indicator of either Mesp1-Cre, Dermo1-Cre or Wnt1-Cre activation in E14.5 embryos. Staining for ALP (below lacZ-stained sections) revealed osteogenic cells and the coronal suture. Punctate lacZ staining is apparent in the prospective coronal suture, parietal bone, and dermis of Mesp1-Cre;R26R and Dermo1-Cre;R26R embryos. Wnt1-Cre resulted in robust lacZ staining for the frontal bone (FB) and meninges (M). (D-G) Immunostains for Jagged1 to assess the influence of Mesp1-Cre, Dermo1-Cre or Wnt1-Cre on Jagged1 protein. Note Jagged1 expression in ectocranial layer (above ALP) and in prospective sutural cells (arrow). In Mesp1-Cre mutant, Jagged1 is selectively lost in sutural cells. In the Dermo1-Cre mutant, Jagged1 is reduced in both the ectocranial layer and suture. In the Wnt1-Cre mutant, Jagged1 is unaffected. (H-L) We produced mice with the floxed Jagged1 allele in combination with the indicated Cre lines. Mesp1-Cre;Jagged1cko/cko embryos died around E13.5-E15.5; consequently we examined the morphology of the developing coronal suture at E14.5 by means of whole mount ALP staining (H, I). Mesp1-Cre;Jagged1cko/cko mutants exhibited a narrowing of the prospective coronal suture (CS) (I, arrow). We examined the skulls of Dermo1-Cre;Jagged1cko/cko and Wnt1-Cre;Jagged1cko/cko mice at P21 by staining with Alizarin Red S (J-L). Note that coronal synostosis in the Dermo1-Cre;Jagged1cko/cko mutant (K, arrows). Sutures of Wnt1-Cre;Jagged1cko/cko mice were normal, but an ossification defect was apparent in the frontal bone (L, arrow). (M, N) To assess the boundary between the coronal suture and adjacent bone territories we produced mice with the R26R allele with Mesp1-Cre;Jagged1cko/cko (N). Note substantial numbers of lacZ positive cells in the frontal bone territories (N, arrowheads). Heads were sectioned as in Fig. 1. CS, coronal suture; FB, frontal bone; M, meninges; PB, parietal bone; SS, sagittal suture. Scale bars: 50 μm in A-G, M, N; 500 μm in H, I; 1mm in J-L.