Fig. 4.

Mesenchymal cell density and morphology are altered according to the regenerative stage. (A-C) Quantification of average DAPI intensity (in arbitrary units, a.u.) in mesenchymal cells along the PD axis of blastemas at 24 hpa (A), 48 hpa (B) and 72 hpa (C). n=7 sections, 3 fish/condition. (D-F) Representative DAPI-stained longitudinal sections of blastemas at 24 hpa (D), 48 hpa (E) and 72 hpa (F). (G-I) Quantification of average space (a.u.) between mesenchymal cells along the PD axis at 24 hpa (G), 48 hpa (H) and 72 hpa (I). n=9 sections; 3 fish/condition. (J-L) Representative anti-GFP-stained longitudinal sections of ctgfa:eGFP transgenics at 24 hpa (J), 48 hpa (K) and 72 hpa (L). (M) Quantification of average cell aspect ratio of mesenchymal cells at 24, 48 and 72 hpa, in which y is the minor axis of the cell and x the major cell axis. A perfect circular shape corresponds to a ratio between y and x of 1. P corresponds to proximal; D to distal regions. ***P<0.0001; two-tailed, non-parametric Mann–Whitney test. n=45 cells/condition; 5 cells randomly selected/image; 9 sections; 3 fish/condition. (N-R) High magnification images of the boxed areas in J-L highlight cell morphology of blastema cells at 24 hpa (N); 48 hpa proximally (O) and distally (P); and 72 hpa proximally (Q) and distally (R). Dashed lines indicate amputation plane. Scale bars: 50 µm. Medial blastema areas were considered for all measurements: shadows indicate the s.e.m. for each curve.