LOW-VOLTAGE BACKSCATTERED ELECTRON IMAGING OF NON-COATED BIOLOGICAL SAMPLES IN A LOW-VACUUM ENVIRONMENT USING A VARIABLE-PRESSURE SCANNING ELECTRON-MICROSCOPE WITH A YAG-DETECTOR

A variable-pressure scanning electron microscope (VP-SEM) equipped wit h a high-sensitive backscattered electron (BSE) detector of the YAG ty pe was applied to studies of biological tissue samples. The rat kidney and trachea were fixed, dehydrated in ethanol, critical point-dried a nd examined in the VP-SEM under a specimen chamber pressure of 1 to 15 0 Pa. The high-resolution surface images of the non-coated specimens w ere obtained in a low-vacuum (1-20 Pa) environment at an accelerating voltage of 5 kV, while the images at 10-20 kV contained information be neath the surface of the specimens. The observation in the VP-SEM equi pped with YAG detector in a low-vacuum (1-20 Pa) environment at low (3 -5 kV) accelerating voltages is useful for the three-dimensional analy sis of the surface morphology of biological non-coated samples.