Transmission electron microscopy of sheathed ericoid mycorrhizae synthesized <i>in vitro</i> between the basidiomycete JPK 87 and <i>Vaccinium vitis-idaea.</i>

<p>1A) Transversal section through a hyphal sheath, showing abundant extraradical hyphae (EH); a hypha (arrow) narrows its diameter while penetrating the host cell wall (CW) and then expands again in the lumen of a host rhizodermal cell (RC). The intracellular hypha is surrounded by the host plasma membrane (arrowhead). Bar = 5 um. 1B) Thick extraradical hypha (EH) penetrates the cell wall (CW) of a host rhizodermal cell (RC) at two entry points (arrowheads). The intracellular hypha (IC) is surrounded by a material apparently derived from the host cell wall (arrows) deposited in the space below the host plasma membrane. Bar = 1 µm. 1C) Extraradical hypha (EH) penetrates the host cell wall (CW), its intracellular phase (IH) is surrounded by the host plasma membrane (arrowhead) and the cell wall-derived material (arrows). Bar = 1 µm. 1D) A dolipore with perforated parenthesomes (arrows) of an intracellular hypha. Bar = 0.2 µm.