Transmission electron microscopy of critical point dried tissue after observation in the scanning electron microscope

Embryonic and adult rodent tissues were fixed and prepared for scanning electron microscopy by dehydration in ethanol followed by critical point drying with liquid carbon dioxide or Freon 13 (E. I. du Pont de Nemours, Inc.). After coating the dried specimens with evaporated metal, the tissues were studied by scanning microscopy. The same tissues were subsequently embedded in Epon‐Araldite, thin sectioned and examined by transmission electron microscopy. The cytological details in these specimens were comparable to tissues embedded directly, without drying or metal‐coating. With this technique it is possible to identify with greater certainty the structures responsible for surface contours revealed by the scanning electron microscope.