Fig. 7

Fig. 7

Osteoblasts in the caudal fin populate the blastema but remain fate restricted. (A–L) Longitudinal sections of the caudal fin of Tg(dusp6:Cre-ERT2, EAB:EGFP-FlEx-mCherry) Class 3 mosaic animals showing mCherry expression in osteoblasts (A, E, I, M, red) and stained with indicated antibodies (B, F, J, N, green) and with Hoechst to mark nuclei (C, G, K, O, blue). The three-color overlays are shown in (D, H, L, P). (A–D) Osteoblasts contribute to the blastema. A fin section observed for mCherry expression and immunostained with zn-3 antibodies to mark osteoblasts. White arrows indicate mCherry⁺ cells (red) in the blastema that co-localize with zn-3⁺ osteoblasts (green). The dashed yellow line marks the amputation site and the dashed white line indicates the epidermis–blastema boundary. (E–H) Osteoblast-derived blastema cells proliferate. A fin section from the same animal in (A–D) stained with anti-dsRed antibodies to detect mCherry expression (red) and with anti-PCNA antibodies (green) to mark proliferating cells. White arrows indicate mCherry⁺/PCNA⁺ intra-ray fibroblasts in the blastema. The border between epidermis and blastema is marked with a white dashed line. (I–P) Osteoblasts do not change fate during regeneration. Stained fin sections from the same Tg(dusp6:Cre-ERT2, EAB:EGFP-FlEx-mCherry) Class 3 mosaic animal prior to amputation (I–L) and 7 dpa (M–P). mCherry expression is red and anti-zn-3 antibody staining marks osteoblasts in green. The white arrows mark cells that are both mCherry and zn-3 positive.