Acellular fibrin scaffold implants in adult rat myocardium. Masson's trichrome staining of scaffold implants in cross section. Unmodified scaffolds after (A, F) 1 day and (B, G) 7 days, aprotinin scaffolds after (C, H) 7 days, and FXIII scaffolds after (D, I) 7 days and (E, J) 14 days of implantation. Black arrows indicate fibrin implant material, white arrows indicate loose collagen deposition, arrowheads indicate examples of infiltrated neutrophils. Scale bars=100 μm in (A–E), 50 μm (F–J). Color images available online at www.liebertpub.com/tea