mRNA expression of MMP-1 and MMP-13.

<p>A–D. MMP-1 <i>In situ</i> hybridization of sections of frontoparietal bone from various stages (antisense probes), 20× magnification. A′–D′. 40× magnification of same area. E. Representative sense probe of stage 60 to demonstrate lack of non-specific staining. Brown staining represents positive localization, blue represent hematoxylin counterstaining. F–I. MMP-13 <i>In situ</i> hybridization of sections of frontoparietal bone from various stages (antisense probes), 20× magnification. F′–I′. 40× magnification of same area. J. Representative sense probe of stage 60. Note increased brown staining in Stage 56 and 60 with both probes.