The cellular and collagen composition of the foreign body reaction to solid and porous implants is pore-size dependent. Representative Masson’s Trichrome photomicrographs show histological responses based on pore size. Collagen is shown in blue, cellular cytoplasm in red, and cell nuclei in black. (A) non-porous implants have a dense FBC at the implant edge, (B) 34 µm porous scaffolds have highly cellular infiltrate, and (C) 160 µm porous scaffolds have a cellular infiltrate that is much richer in collagen than 34 µm scaffolds. Reprinted from Annals of Biomedical Engineering, “Porous implants modulate healing and induce shifts in local macrophage polarization in the foreign body reaction,” 42, 1508–1516 by Sussman, E. M.; Halpin, M. C.; Muster, J.; Moon, R. T.; Ratner, B. D. Copyright Annals of Biomedical Engineering 2013, with permission of Springer.