Fig. 9

Schematic representation of caudal fin vascular development. (A) Initiation of caudal fin development through vein-artery sprouting, indicated throughout the figure by red-blue arrows. (B) The posterior circulatory loop consists of PCLa connected to DA, and PCLv connected to PCV. (C) Ventral sprouting from PCLv. (D) Ventral sprouting from the DA/PCV junction through plexus sprouting (yellow arrow). (E) At 2 wpf (5.2 mm standard length), the PFP expands to form the dPFP and vPFP (yellow arrows), and the CFP expands into a growing fin through vein-artery sprouting (red-blue arrows). (F) At 3 wpf (6 mm standard length), the CFP remodels into a two-vessel pattern consisting of a BEA and a main vein, and the IP forms (yellow arrow). (G) Ancillary vein sprouting (blue arrows) establishes a three-vessel pattern, vein-artery sprouting continues distally (red-blue arrows) and the IP expands (yellow arrow). (H) Intussusceptive angiogenesis generates new arterial side branches (black arrows). (I) Inter-ray connections are formed (black arrow). Abbreviations: BEA, bone-enclosed artery; CFP, caudal fin plexus; DA, dorsal aorta; IP, interlaced plexus; IRC, inter ray connection; PCLa, posterior circulatory loop artery; PCLv, posterior circulatory loop vein; PCV, posterior cardinal vein; PFP, proximal fin plexus; dPFP, dorsal proximal fin plexus; vPFP, ventral proximal fin plexus.