Fig. 5

Intra-ray fibroblasts are a proliferating component of the blastema. (A–L) Longitudinal sections of Class 2 mosaic fins from Tg(dusp6:Cre-ERT2, EAB:EGFP-FlEx-mCherry) harvested 2 dpa and monitored for mCherry expression (A, E, I, red) and immunostained with indicated antibodies (B, F, J, green). Nuclei are stained with Hoechst (C, G, K, blue), and the three-color overlay is shown in each case (D, H, L). (A–D) Cells derived from intra-ray fibroblasts populate the blastema at 2 dpa. The section shows mCherry expression (A, red) and is immunostained with anti-tenascin C (tenC) antibodies (B, green). The white arrow indicates mCherry⁺ intra-ray fibroblasts and the white dashed line denotes the boundary between epidermis and blastema. (E–H) mCherry⁺ intra-ray fibroblasts do not express markers for osteoblasts in regenerating tissue. mCherry⁺ cells are shown in red and zns-5 antibodies detect osteoblasts (F, green). White arrows indicate mCherry⁺ cells in the blastema that do not co-localize with zns-5⁺ osteoblasts (yellow arrow). The white dashed line indicates the boundary between epidermis and blastema. (I–L) Intra-ray fibroblasts are a source of proliferating cells in the blastema. A 2 dpa section co-stained with anti-dsRed antibodies to detect mCherry⁺ cells (I, red) and anti-PCNA antibodies to detect proliferating cells (J, green). The white arrows indicate mCherry⁺/PCNA⁺ intra-ray fibroblasts in the blastema. The yellow arrow in panel (L) marks an mCherry⁺/PCNA intra-ray fibroblast. The border between epidermis and blastema is marked with a white dashed line.