Fig. 7

The silk gel implants observed by 2D (a–d) and CEUS (e–h) at day 12, 16, 18 and 20. As time went by, more microbubbles infused into the silk gel, indicating the progression of neovascularization. At day 20, microbubbles in the silk gels had a similar density to those in the surrounding tissues and the silk gel implants could not be distinguished (h), arrows, outline of silk hydrogel implants