The tissue adjacent to the devices was vascularized but cells inside the devices are not viable. (A and B)- Histological analyses (stained with H.E.) of the environment around the device. Arrows show new blood vessels, which reveals that it is biologically inert and promotes neovascularization, and that the cells are inside the device. No viable endostatin producer cells were noted; (A) Histological analyses of the environment around the device which was pre-implanted;(B) Histological analyses of the environment around the device which was implanted concomitantly with the cells.