Freeze‐fracturing for low‐temperature scanning electron microscopy of Hartig net in synthesized Picea abies – Hebeloma crustuliniforme and – Tricholoma vaccinum ectomycorrhizas *

SUMMARY Rapidly frozen ectomycorrhizal roots were freeze‐fractured under high vacuum in a dedicated cryo‐preparation unit and investigated in the frozen, partially freeze‐dried, or fully hydrated state. Tangential, radial and occasional transverse surface views of Hartig net were obtained after freeze‐fracturing. Protoplasmic and exoplasmic fracture faces of the fungal plasmalemma und occasional fractures between the fungal cell wall and the extracellular matrix were seen. Primary pit‐fields with plasmodesmata occurred in non‐ectomycorrhizal parts of the root as well as in small gaps of Hartig net. Septa with dolipores were observed in the finger‐like complexes of the Hartig net.