Lack of endochondral ossification and closure delay in <i>Axin2^−/−</i> PF-sutures.

<p><b>A</b>, pentachrome staining of PF-sutures from <i>Axin2^−/−</i> and wild type mice during the timing of physiological closure reveals an involuting ectopic cartilage in the suture mesenchyme of <i>Axin2^−/−</i> PF-sutures, while endochondral ossification occurs in wild type PF-sutures. Closure is delayed in <i>Axin2^−/−</i> PF-sutures compared to wild type PF-sutures. <i>Axin2^−/−</i> PF-sutures closure is observed at day P25. <b>B,</b> measurements of the distance between the approaching osteogenic fronts of endocranial and ectocranial bone plates in <i>Axin2^−/−</i> and wild type PF-sutures show significantly greater distances between the osteogenic fronts of the endocranial bone plates in <i>Axin2^−/−</i> PF-sutures from P7 to P17. Scale bar: 100 µm.