Scanning electron and light microscopy of appressorium development in Piptocephalis unispora (Mucorales)

Appressorium development in the mycoparasite Piptocephalis unispora was studied by means of scanning electron microscopy using the techniques of critical point drying, sputter coating and light microscopy. The germ tube which contacts both the young host hypha or a germinating spore swells at the tip to form an appressorium closely adpressed to the surface of the host. Lateral proliferation of hyphae may occur from the mature appressorium. Factors affecting the sites of appressorium development are suggested and their significance discussed.