Anatomy and morphometry of myocardial capillaries studied with vascular corrosion casting and scanning electron microscopy: a method for rat heart.

The present paper describes a procedure for preparing vascular corrosion casts of rat myocardial microvasculature. Essential components of the procedure include: partial "self clearing" of the heart in vitro; cardiac arrest by infusion of KCl; retrograde aortic root infusion of Mercox-Sevriton casting resin; KOH digestion of ventricular tissue; and desiccation and mounting of casts for scanning electron microscopy. About 50% of rats yielded complete casts. Vasculature closely paralleled muscle fiber orientation. Capillary beds characteristically exhibited branching, many intercapillary cross bridges, and occasional coiling. Average capillary cast diameter (5.6 microns) and intercapillary distance (15 microns) are comparable to results from in vivo studies. From preliminary calculations, vascular volume represents about 10% of the ventricular walls. These data indicate that vascular corrosion casts may be useful in the analysis of pathologic states and in determining the role of potential therapeutic interventions.