USE OF LOW-TEMPERATURE SCANNING ELECTRON-MICROSCOPY TO OBSERVE FROZEN-HYDRATED SPECIMENS OF NEMATODES

Frozen hydrated specimens of Pratylenchus agilis and dauer larvae of S teinernema carpocapsae were observed with low-temperature field emissi on scanning electron microscopy. This new technique provides informati on about the surface features of nematodes and also allows specimens t o be fractured to reveal their internal structure. Furthermore, both h alves of fractured specimens can be retained, examined, and photograph ed either as two-dimensional micrographs or as three-dimensional image s for stereo observation (stereology) or quantitative measurements (st ereometry). This technique avoids artifacts normally associated with p rocedures required to prepare nematodes for examination in the transmi ssion and scanning electron microscopes, such as chemical fixation, de hydration, and sectioning or critical point drying.