Freeze-fracture autoradiography. Progress towards a routine technique.

Freeze-fracture autoradiography was introduced in 1976 as a new technique for the autoradiography of diffusible compounds at the electron microscope level. With the original approach coating of the frozen replicated specimens was performed in a cryostat at atmospheric pressure. Ice contamination of the specimen surface acting as an outstanding source of artifacts was thereby not excluded. With the use of a specially designed coating device and volatile spreading substances it was made possible to coat the frozen replicated specimens in the maintained vacuum of the freeze-fracture plant. In this complicated technique we have recently extended the freeze-fracture autoradiography to labeled frozen-dried "half" membranes of red blood cells.