Transmission electron microscopy on allograft walls.

ECs covering intimal surface (A); underneath the intima, fibroblasts (Fbs) with dilated endoplasmic reticulum (B; asterisks), synthesizing collagen fibrils from fibril-forming channels (C) and elastin fibers (e) (D) or with abundant myofilaments (mf) (E). Erythrocytes (Er)-containing capillaries coated by ECs joined by tight junctions (opposite arrowhead in inset) (F). Amyelinic nerve fibers (NF) encapsulated by Schwann cells (SC) (G). Blood vessels (arrows) in media and adventitia after trichrome staining (H). Neural marker PGP9.5-expressing nerve fiber (arrows) in media (I). Magnifications in I: A 3 µm; B 1 µm; C, D, G 0,5 µm; E, F inset 0,25 µm; F 2 µm; H, I 250 µm. Transmission electron microscopy on allograft cusps. ECs onto intimal surface and sub-intimal Fbs (A). Immature intercellular junction (opposite arrowheads) between ECs adhering elauninic fibers (ef) surrounded by fibrillin microfibrils (encircled area) (B). Interstitial myofibroblasts showing intercellular junctions (opposite arrowheads) (C). Interstitial SMCs containing microfilaments (Mf) (D). Fbs with multiple fibril-forming channels (arrow) and adjacent efs (E). Abundant efs in interstitium (F). Magnifications in II: A 3 µm; B, C, E 0,5 µm; D, F 1 µm.