SummaryConventional preparative procedures for the examination of tissues in the electron microscope involve the use of fixatives, dehydration in alcohol or acetone, embedding in plastics and staining. Such procedures remove soluble components and are therefore often unsuitable for chemical analysis of naturally occurring electrolytes. Ultrathin frozen sections of unfixed, unembedded biological tissue can be cut onto dry glass knives, freeze‐dried and viewed in the electron microscope without staining. Morphological detail is sufficient to identify cell types and ultrastructure. X‐ray microanalysis in the analytical electron microscope (EMMA‐4) has shown that highly soluble electrolytes can be detected and that intracellular compartments are ret