Histological cross-sections of stomach PTFE implants containing transduced smooth muscle cells. Tissues in panels 1 and 2 were obtained at 12 months postsurgery from a rat that had a hematocrit of 62%, fixed in formalin, and stained with H&E. PTFE implants containing Epo-secreting vascular smooth muscle cells unlabeled (panel 3) or marked with DiI (panel 4) were removed 2 months postsurgery from a rat with a hematocrit of 67%, frozen, sectioned, and photographed using a Nikon Microphot FXA equipped with a rhodamine filter. PTFE material is denoted P, and mucosal tissue as M. (Panels 1, 2, and 4: ×40 original magnification; panel 3: ×100 original magnification.