2 DIFFERENT PATHWAYS OF GLOMERULAR ENLARGEMENT IN ADULTS WITH FOCAL AND SEGMENTAL GLOMERULOSCLEROSIS - A MORPHOMETRIC STUDY

The renal biopsy specimens obtained from 15 adults with focal and segm ental glomerulosclerosis (FSGS) and 15 adults with minimal change neph rotic syndrome (MCNS) were morphometrically analyzed using light and e lectron microscopy. Moreover, initial biopsy specimens obtained from 1 0 adults who were diagnosed as MCNS and developed FSGS, based on repea t biopsy findings ('MCNS'-FSGS), were also analyzed using electron mic roscopy. After comparing the actual values between the groups of FSGS and MCNS, the mean glomerular volume, the capillary volume per a glome rulus, the capillary filtration surface per a glomerulus, and the capi llary diameter (Cap-D) were all larger in the FSGS group than in the M CNS group. In regard to the morphological values in the 'MCNS'-FSGS gr oup, both values of the surface density of the capillary filtering sur face and the capillary diameter at the first biopsy specimens as well as those in the FSGS group were higher than those in the MCNS group. W hen analyzing the structural parameters, in the FSGS series, we found a high association of the percentage of obsolescent glomeruli (%SG) wi th the mean glomerular volume, the capillary volume per a glomerulus, the capillary filtering surface per a glomerulus and the capillary len gth per a glomerulus, however we failed to demonstrate the correlation between the %SG and the Cap-D. Thus, the glomerular structure in the 'MCNS'-FSGS patients, even at the first renal biopsy, resembled that i n FSGS, suggesting FSGS to be a distinct entity from MCNS. These data indicate that the enlargement of the capillary volume, resulting from the widening of the capillaries, was the initial structural event for adults with FSGS, while the elongation of the capillaries appeared to reflect some compensatory process for the decrease in the functioning nephron.