Fig. 5. Intramembranous ossification is excessive near Kif3a-deficient synchondroses. Parasagittal serial sections of P7 control (A-D) and mutant (E-H) spheno-occipital synchondroses were processed for staining with fast green/Safranin O (A,E) or in situ hybridization analysis of the indicated genes (B-D,F-H). (A-D) In controls, notice the presence of the intramembranous bone collar adjacent to the pre-hypertrophic and hypertrophic zones (arrowheads) and its absence near the proliferative and resting zones (arrows), as is to be expected. Notice instead that the intramembranous bone had formed all along the flank of the Kif3a-deficient synchondrosis (E-H). Scale bar: 75 µm in H for A-H.