Confocal microscopy, computer modeling, and quantification of glomerular vascular corrosion casts

Corrosion-casted capillary systems of the kidney glomerulus were imaged with confocal microscopy because of the fluorescence properties of the casting plastic. Acquisition of a z-series through the glomerular capillaries provided three-dimensional data sets from which surface-rendered models were generated. These models could be rotated and viewed from any angle and also contained quantitative information allowing cast surface area and volume measurements to be calculated. The computer-generated models were also skeletonized to form a one-voxel-thick skeleton of the original model. The skeleton, exhibited the three-dimensional topology and network of the capillary bed, and interior capillary relations could also be viewed. Quantitative information such as the total capillary length and number of capillary intersects was calculated from the skeletonized model. Extending this method to noncorroded kidney specimens revealed not only the casted vessels but also cellular features of the adjacent tissues surrounding the capillaries.