Regeneration in the Amphioxus (Branchiostoma platae)

Regeneration in amphioxus, an animal deprived of phagocytes, was studied fo llowing the amputation of the distal part of the tail. After 15 days, a bud had already grown from the healed wound and continued to grow up to the 14 0th day tend of the observation), when it assumed the shape of an almost re stored tail. This tail consisted of a skin epithelium resting on a fragment ed basal lamina whit disorderly arranged collagen fibres, not arranged in f ish spine pattern. In the underlying connective tissue, vessel-like structu res occur, whose walls are formed by endothelial-like cells, without an int erposed basal lamina, resting on collagen fibres arranged in the fish spine manner. The migration of endotelial-like cells to the connective tissue in the absence of phagocytes is unusual, for in chordates neo-vascularization normally requires them.