Fig. 6. Capillary-like tube formation in vitro by cells sprouted from HITA rings. At different stages of confluence (A,B: non confluent; C,D: subconfluent), cells isolated from collagen gel after performing a ring assay formed a network of tubes (arrowheads) when stimulated with VEGF (A,C). No tubes were visible in controls exposed to basal medium only (B,D).