Morphometry of kidney biopsy: influence of section thickness variation
Abstract
We studied the intraobserver variation in estimates of morphometric glomerular parameters when section thickness varied. Paraffin sections 1, 2, 3, 4, and 5 µm thick were cut in series of a kidney biopsy with an automatic electronically steered microtome. The sections were stained with Masson trichrome stain and glomeruli common to all five sections selected for analysis. One observer studied the sections five times to estimate the variation limits within one biopsy. As expected, the number of glomerular nuclei increased with increasing thickness of sections. In reference to the area of glomeruli the range of variation between the five sections was 41 per cent of the mean. Variation of individual estimates clearly increased with increasing thickness of section. The mean of the estimates of the volume fraction of the mesangium slightly increased with increasing thickness. In general, variation was least in thickness range of 1-3 µm. The variation in thicker sections seemed to be due to superimposition of structures which led to difficulties in interpretation. The surface density of glomerular basement membrane showed the smallest variation in sections 3-4 µm thick. This shows that certain measurements will not give the most reliable results in the thinnest sections.