Three-dimensional modeling of renal glomerular capillary networks

To quantitatively characterize three-dimensional (3D) vascular patterns based on the path length distribution in networks.

Volume data were stacks of confocal fluorescence images of renal glomeruli, obtained using a confocal laser scanning microscope and spanning 60-130 microns in the z axis. After manual editing to remove nonglomerular components, transverse sections of glomerular capillary lumens were segmented automatically using two-dimensional morphologic filters. The center points and the overlap (between adjacent sections) of lumens segmented in the x vs. y plane were used to derive a graph (i.e., a multiply connected network) for each glomerulus. The average degree and the distance between connected nodes were used to derive the number of graph edges and the overall length of the capillary network.

Renderings of the 3D reconstructions demonstrated well the lobular structure of the glomerular tufts. Mean capillary length ranged from 53 to 180 microns in 10 glomeruli. Total capillary length ranged from 3,500 to 9,500 microns (mean 5,833).

Structural measurements based on confocal data require less effort than do measurements based on serial sections and make detailed study of diseased glomerular populations practical.