Fig. 2

Vessel healing and anastomosis. Time-lapse images from a representative regenerating fin ray of TG(fli1:EGFP)^y1 show healing and anastomosis of amputated blood vessels during early regeneration. (A) After amputation (0 hpa), severed vessels exhibit openings at the amputation plane (white arrow, artery; white arrowheads, veins). (B) Higher magnification of the distal ends of the severed vessels in (A) show the openings (red arrowheads). (C) These vessels are sealed by 24 hpa (note rounded ends) and sprouts (arrowheads) are frequently observed in (D) enlarged image of the amputation plane. (E) By 48 hpa, cut ends of blood vessels have formed anastomotic bridges between the artery and veins within the same fin ray. Blood flow has resumed through these bridges by this stage (not shown). (F) Higher magnification of the reconnected vessels of (E) shows anastomotic bridges connecting the artery and the two veins (yellow arrows). (G) By 80 hpa, we observe new blood vessels sprout from the distal face of anastomotic bridges (yellow arrowhead). Red arrows point to amputation plane. Diffuse green is autofluorescence from fin ray (possibly bone matrix). Scale bar, 100 μm.