A novel hinged device for freeze-fracturing of cell monolayer in the Balzers freeze-etch unit is described. It is economical on biological material and enables oriented adsorption of sheet-like membrane fragments. For freeze-fracturing 'by hand' a monolayer is formed on a positively charged piecie of mica (with polylysine) and this is covered with another piece of mica, thin brass plate of filter paper. Such a sandwich is frozen in liquid nitrogen and fractured by means of forceps. Several modifications of this technique as well as practical examples are described. Among possible application are: negative staining of intramembranous protein particles; chemical or physical analyses of single membrane leaflets; identification of protein complexes by immunoelectron microscopy, etc.

Freeze-etch replicas of a hylauronic acid matrix were visualized by electron microscopy. In water a coarse branching fibrillar network of hyaluronic acid aggregates was seen. The high solvent permeability of this matrix suggests that the spaces observed are relatively devoid ofunaggregated polymer. Addition of calcium disordered the matrix, resulting in a more dispersed felt of polymer.

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A procedure for electron microscope autoradiography of red blood cell ghosts or their outer membrane leaflets is described: sheep erythrocytes, attached to positively charged mica, were either lysed and air-dried, or freeze-fractured "by hand" and freeze-dried. This was followed by shadowing and carbon replication; coating with photographic emulsion; exposure in darkness at 277 K; developing and fixation; carbon coating; floating off the mica and mounting on grids. Erythrocytes iodinated with 125I using the lactoperoxidase reaction were used as a test object. The efficiency of the procedure was found to be between 3.4% and 5.6%.