Small finfold and vascular plexus in young caudal fins of prp mutants. (A) Wild-type (WT) and (B) prp 2 day post-fertilization (dpf) embryos showing the small-finfold phenotype in prp. (C) WT and (D) prp larvae, at ∼ 13 dpf, showing the small-finfold phenotype throughout the larval stage in prp. Arrows in panels A–D denote the distal edges of the caudal finfolds. n, notochord. (E–H) Time lapse images of the developing vasculature between around 20 and 40 dpf in a WT caudal fin. (E) Fin vessels (arrow) growing from the posterior ends of axial vessels located below the vertebral column (vc). (F) Pioneer vessels (arrows) branching and growing dorsally and ventrally. (G) Fin vessels were organized into a radial pattern (arrows) soon after the vessels grow into the caudal fin. (H) Within a week, the mature 16–18-ray pattern of the fin vasculature was established. (I–L) Early development of the caudal fin vasculature in a representative prp mutant. (I, J) Pioneer fin vessels (arrows) growing out and branching normally in prp fish. (K, L) Instead of forming a radial pattern, the fin vessels of the prp mutant formed a large vascular plexus which expanded into the entire caudal fin (arrow in L). (M, bright light; N, fluorescence) In WT fish, the bony fin rays or lepidotrichia were stained by calcein fluorescent dye (arrows; Du et al., 2001) and were organized into a radial pattern associated with the vessels. (O, bright light; P, fluorescence) Fin rays of the prp mutant were often curved and juxtaposed and even fused (arrows). Anterior, left; dorsal top. Scale bars, 150 μm for panels A–D.
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