ABSTRACT
In 1961, Moor et al. incorporated a liquid-nitrogen-cooled ultramicrotome into a vacuum chamber and this prototype has served as a model for all subsequent freeze etch units. Freeze etching is a specialized ultrastructural technique in which frozen samples are fractured under vacuum with or without subsequent partial sublimation of the surrounding ice. This chapter outline the steps involved in freeze etching. The use of freeze fracture techniques has revealed a variety of specialized structures within the plane of the plasma membrane of a variety of pulmonary epithelial cells. The morphological characterization of intercellular junctions between endothelial and epithelial cells of the lung has relied on the freeze fracture technique. To broaden the usefulness of freeze fracture in cell biology, methods have been devised to combine a variety of labeling techniques with freeze fracture. These have not, thus far, been applied to the study of lung cells. Two of these methods are: freeze fracture autoradiography and colloidal gold labelling.
