Measurements on thin hydrated cryosections show that x-ray microanalysis is limited to areas greater than l-mu-m2 and to the major elements because of radiation damage; the maximum allowed doses are only approximately 104 e/nm2 for analysis of hydrated sections. For freeze-dried cryosections low-dose STEM micrographs show good structural preservation down to the level of single membranes. The small probe size and high stability of the low temperature stage in the HB501 STEM facilitates high resolution analysis of 10-nm scale structures in such sections, although certain detail is lost on irradiation. The sensitivity for microanalysis of elements such as calcium in small organelles is in the range of a few tens of atoms.
