Fig. 7. Cell wall thickenings in mycelium from P.p.n. strains. (A-D) Confocal laser scanning microscopy of Congo Red-stained EX11-1 CBEL⁺ (A,C) or EX11-4 CBEL^- (B,D) hyphae grown either on a cellophane (A,B) or a polycarbonate membrane (C,D) placed on top of V-8 agar medium. Note the presence of patches of Congo Red-stained material (arrows) along the CBEL^- EX11-4 hyphae grown on either substrate. Image acquisition parameters were adjusted to optimize contrast in images C and D. Bars, 40 µm. (E-G) Transmission electron microscopy of PATAg-stained hyphae grown on a cellophane membrane placed on top of V-8 agar medium. (E) Transverse section of a hypha from the EX11-1 CBEL⁺ strain. The PATAg-stained cell wall appears as an electron dense layer (asterisk) and the plasmalemma-cell wall interface is strongly labelled (arrow). (F,G) Oblique sections of EX11-4 (F) or EX3-3 (G) CBEL^- hyphae. Note the PATAg-stained papillae-like paramural deposits (P) between the cell wall (asterisk) and the plasma membrane (arrow). Bars, 1.5 µm.