HUMAN GLOMERULAR GROWTH DURING CHILDHOOD - A MORPHOMETRIC STUDY

Morphometric measurements of glomerular size were made on renal biopsy specimens obtained from 16 children with minimal change nephrotic syndrome (MCNS) and 16 with isolated recurrent haematuria (RH), whose ages ranged from 1.8 to 15.2 years. Glomeruli were normal on light and electron microscopy, and immunofluorescence was essentially negative. Tracings were made of the outlines of glomerular capsules, tufts, and individual capillary lumens; using computerized digitometry, the mean areas of each item were determined. The number of capillary lumens per glomerulus was counted automatically. From these data, the mean mesangial area was also calculated. Mesangial cells were counted in at least 100 distal mesangial areas per biopsy. The mean glomerular capsular area (GCA) correlated well with the mean glomerular tuft area (GTA) but frequent capsular artefacts rendered the former measurement less suitable for comparison with diseased glomeruli. The mean GTA correlated significantly with age and body surface area in both MCNS and RH, as did the number of capillary lumens per glomerulus, but the mean capillary lumina area showed no such correlations. The mean mesangial area increased with age in proportion to GTA, whereas mesangial cell counts remained normal. These findings indicate that glomerular growth during childhood is proportional to body growth, and are consistent with capillary subdivision as the mechanism of enlargement