Fig. 12. SEM showing transverse section from the midportion of an inoculated wound after 4 weeks. Note the large gum ducts and marked lack of differentiation of callus tissue (CT) compared with control wound (Fig. 8). Hyphae are visible growing along exposed wood surface (arrow) and tissue is generally embedded in a mass of gum (G). X42. (From Wisniewski et al., 1984).