Vascular corrosion casting: Review of advantages and limitations in the application of some simple quantitative methods

Vascular corrosion casting has been used for about 40 years to produce replicas of normal and abnormal vasculature and microvasculature of various tissues and organs that could be viewed at the ultra-structural level. In combination with scanning electron microscopy (SEM), the primary application of corrosion casting has been to describe the morphology and anatomical distribution of blood vessels in these tissues. However, such replicas should also contain quantitative information about that vasculature. This report summarizes some simple quantitative applications of vascular corrosion casting. Casts were prepared by infusing Mercer resin or diluted Mercer resin into the vasculature. Surrounding tissues were removed with KOH, hot water, and formic acid, and the resulting dried casts were observed with routine SEM, The orientation, size, and frequency of vascular endothelial cells were determined from endothelial nuclear imprints on various cast surfaces. Vascular volumes of heart, lung, and avian salt gland were calculated using tissue and resin densities, and weights. Changes in vascular volume and functional capillary density in an experimentally induced emphysema model were estimated from confocal images of casts. Clearly, corrosion casts lend themselves to quantitative analysis. However, because blood vessels differ in their compliances, in their responses to the toxicity of casting resins, and in their response to varying conditions of corrosion casting procedures, it is prudent to use care in interpreting this quantitative data. Some of the applications and limitations of quantitative methodology with corrosion casts are reviewed here.