Measuring the volume density of the glomerular mesangium

Volume density (Vv) is a morphometric parameter used to detect pathological changes within renal tissue. To establish the most efficient technique, Vv of the mesangium in renal biopsies was studied. First, a digitizing tablet was used to trace mesangial and total glomerular areas, subsequently used to calculate Vv of the mesangium. Secondly, a point counting technique was tested using either a 16-point or an 81-point grid; the number of grid points falling on the mesangium and glomerulus was used to calculate mesangial Vv. The digitizing tablet, the 81-point grid and the 16-point grid all gave equivalent Vv for the 15 biopsies. The 81-point grid and the 16-point grid were, respectively, 1.9 and 3.2-fold faster than the digitizing tablet. Since all techniques gave comparable results, the 16-point grid was the most efficient.