Model of vascular repair in the zebrafish spinal cord. (a) Organization of the SC vasculature in adult zebrafish. Ventral arteries give rise to vessels that run along the ependymal canal and branch as grey matter capillaries. These capillaries aggregate around collecting dorsal veins, forming vascular clusters. Small calibre vessels are supported by pericytes. (b) SCI triggers early endothelial proliferation. New blood vessels rapidly invade the injured tissue and are observed in proximity of glial projections and growing/spared axons. (c) Rostral and caudal growing vessels anastomose in the injured region and become perfused between 5 and 7 dpi, as the glial and axonal bridges are formed. The initial vascular repair creates a network of irregular vessels. Pericytes are recruited to new blood vessels from 7 dpi until 30 dpi, but vessels remain permeable during this period. (d) Between 30 and 90 dpi the vascular network is remodelled and the BSCB is re-established, allowing for the long-term and functional vascularization of the regenerated SC.
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