Scanning Electron Microscopy of the Nematode-trapping Organs in Arthrobotrys oligospora.

The three-dimensional capture organs of the nematode-trapping fungus Arthrobotrys oligospora are presented in scanning electron micrographs. The fungus was grown directly on agar substrates or on millipore filters or glass cover slips placed on agar substrates. To avoid shrinkage of the soft-walled mycelial material, a fixation in OsO4-vapour was performed, before freeze-drying and coating with Au-Pd alloy. When capture organs were prepared in this way, it was possible to visualize them in their erect position in the scanning electron microscope. Young capture organs, both spontaneously formed and nematode-induced, remained standing better than old ones. An adhesive substance on the capture organs, with the aid of which nematodes are trapped, seems to be visible in these pictures. [ABSTRACT FROM AUTHOR]