SEM of micro-corrosion casts.

The production of micro-corrosion casts suitable for scanning electron microscopy (SEM) is described in this tutorial. The casts are produced by filling an internal luminal system or space with a liquid medium which becomes solid in situ. The surrounding tissue is then removed (corroded) and the resulting replica is dried, rendered conductive, and examined in the SEM. An historical review describes the evolution of the technique and provides perspective for the SEM applications. The criteria which should be fulfilled by the injection medium are listed, and the procedures used for those media which have proven successful, together with their inherent artefacts are described in detail. The two groups of media most commonly used are the rubber compounds and the polymer resins. The latter so faithfully replicate luminal surfaces that a distinction between arteries and veins can be made on the basis of endothelial cell impressions on the surface of the replica. A review of currently used non-SEM techniques provides a comprehensive analysis of the methods used to determine success with SEM micro-corrosion casting, as well as complementary methods for the visualization of vascular and alveolar systems. The paper is illustrated mainly with material from the rat brain vascular system.