Fig. 3

Fig. 3 Vasculature plexus formation, plexus remodeling, and late regenerative angiogenesis. Regenerating blood vessels in wild-type TG(fli1:EGFP)^y1 form plexuses. (A) In 3-dpa regenerates, the regenerating vasculature of each fin ray (three fin rays are shown) consists of a plexus with dense unstructured vessels extending distally from the amputation plane (red arrows). (B) By 4 dpa, the plexus is remodeled into distinguishable arteries and veins in the proximal regenerate (region delineated by red double-headed arrow). A vasculature plexus is still present at the distal end (region delineated by yellow double-headed arrow). Higher magnification of one fin ray of this regenerate is shown in (C). (D) Coincident with plexus remodeling, the plexus becomes smaller (region delineated by yellow double-headed arrow in D and E) in later regenerates as shown in a 6-dpa regenerate. Higher magnification of the delineated plexus in (D) is shown in (E). (F) Low magnification and (G) high magnification of the distal end of an 8-dpa regenerate show that the plexus has been entirely remodeled into arteries (white arrow in G) and veins (white arrowheads in G). (H) The plexus length (as denoted by yellow double-headed arrows in B–E) reaches a maximum of 400-500 µm at 3 dpa and disappears by 8 dpa. After 8 dpa, vessel growth proceeds by sprouting angiogenesis without a plexus intermediate, which we refer to as late regenerative angiogenesis. (I) Enlarged boxed region of the 8 dpa regenerate in (F) shows sprouts (yellow arrows) formed at the distal end of the growing vessel. (J and K) The same regenerating fin rays imaged at 9 dpa and then again at 12 dpa show that regenerating vessels grow without a plexus intermediate. Amputation plane outside field of view. White double-headed arrows denote the distal growing fin ray. Scale bar, 200 μm.