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Fig. 6 TUNEL staining shows no increase in apoptotic cell death in crocc2 mutant larval cartilages. (A-D) Low and (A?-D?) high magnification ventral views of 7 dpf larvae mandibles showing dark staining in apoptotic cells as detected using the TUNEL method. In wild-type animals (A and A?), a few darkly labeled cells are seen throughout the mandible as compared to the negative control samples where no reaction enzyme was added (TdT?; D and D?). In the positive control samples (CyA; C and C?), wild-type (crocc2+/+) larvae were incubated in cyclopamine (CyA) and show numerous darkly stained cells throughout the mandible. MC cells in crocc207/07 mutant animals (B and B?) exhibit patterns of TUNEL staining similar to what is seen in wild-type siblings. Scale Bar = 50 ?m for (A-D) and 10 ?m for (A?-D?). (E, F) Box plots displaying the intensity of TUNEL staining, relative to background staining, in individual MC cells adjacent to the muscle insertion and flanking sites. In both (E) 5 dpf larvae and (F) 7 dpf larvae, there are no significant differences (n.s.) in TUNEL staining between wild-type (blue), crocc2 mutant (red), and wild-type negative control (no enzyme, yellow) cartilages and there is a significant increase in TUNEL stain in the positive control samples (CyA = cyclopamine, purple; *** = P < .0001).