Cryoprotection in electron microscopy

SUMMARY A set of experiments has been undertaken to resolve questions about the cryoprotection factor afforded by cooling specimens in the electron microscope. Two specimens, an n‐alkane (paraffin) and bacterial purple membrane, were prepared and distributed to several laboratories. Radiation damage studies were carried out at these laboratories independently, but following a standard protocol as closely as possible. While it was not possible to make all measurements at all of the laboratories, sufficient data have been obtained to establish a general reproducibility in the overall features of the cryoprotection effect from room temperature to near 4.2 K.