LOW-TEMPERATURE SCANNING ELECTRON-MICROSCOPY OF FROZEN-HYDRATED APPLETISSUES AND SURFACE ORGANISMS

Frozen hydrated buds and epicarp of 'Golden Delicious' apple (Malus do mestica Borkh.) were observed with a low-temperature, field emission s canning electron microscope (SEM). In addition to observing surface fe atures of these specimens, holders were modified to observe fractured specimens. A modified hinged holder retained both halves of a fracture d specimen for examination of the complementary faces of frozen hydrat ed tissues. Low-temperature SEM avoided artifacts, such as extraction, solubilization, and shrinkage, which are normally encountered with ch emical fixation, dehydration, and drying, respectively. The technique allowed observations of well-preserved frozen hydrated structures, suc h as the platelets of epicuticular wax; loosely associated organisms o n plant surfaces, such as spider-mite eggs; delicate structures, such as fungal hyphae; and partially hydrated tissues, such as fruit epicar p and winter bud scales.