A practical guide to the stereological assessment of glomerular number, size, and cellular composition

Abstract

The evaluation of a range of measures in the kidneys, such as developmental stage, rate and success, injury, and disease processes, relies on obtaining information on the three‐dimensional structure of the renal corpuscles, and in particular the glomerular capillary tufts. To do this in the most accurate, comprehensive, and unbiased manner depends on a knowledge of stereological methods. In this article, we provide a practical guide for researchers on how to quantitate a number of structures in the kidneys, including the estimation of total glomerular number, glomerular capillary length and filtration surface area, and the cellular composition of individual glomeruli. Guidance is also provided on how to apply these methods to kidneys at different sizes and levels of maturity.

Introduction to a special issue on kidney development and disease

“…Importantly, his development of these methodologies has directly enabled major advances in the understanding of renal anatomy. Some of these stereological techniques are described in step‐by‐step detail in a review article authored by myself and John's long‐standing collaborator and Monash colleague Prof. Jane Black, with the aim of making these gold standard quantitative approaches accessible to a wider group of researchers (Sutherland, Vojisavljevic, & Black, 2020). Stereology collaborator Prof. Jens Nyengaard presents in this issue a proof‐of‐concept application of the design‐based nucleator technique for estimating nephron number in human kidneys, using CT scanning and biopsy samples (Nielsen et al, 2020).…”

Filtering the good from the bad: A focus on kidney development and disease to celebrate John Bertram's long‐standing career in anatomy and renal research

“…Since then, he has published several other articles relating to stereological applications in the kidney (Akison et al, 2020; Bertram et al, 2000; Brandon et al, 2008; Concalves et al, 2020; David et al, 2010; Hughson, Hoy, & Bertram, 2020; O'Connell et al, 2006). In this Special Issue, Megan Sutherland, Danica Vojisavljevic, and I have written a step‐by‐step guide to stereological analyses of glomeruli that we routinely use in our laboratories (Sutherland, Vojisavljevic, & Black, 2020); these techniques we have developed in close collaboration with John Bertram and the members of his research group. John's close colleague Jens Nyengaard, also internationally recognized for his expertise in stereology and a regular contributor to The Anatomical Record , has also contributed an article to this Special Issue (Nielsen et al, 2020).…”

Renal morphology and glomerular capillarisation in young adult sheep born moderately preterm

“…Eight pieces (two opposing pieces from each quarter of the kidney) were then selected. Using a razor blade slicing device, the eight sampled kidney pieces were sliced at a 2 mm thickness and were sampled using a smooth fractionator approach 35,36 to obtain two sets of 8-10 slices of tissue per kidney for analysis.…”

“…The boundaries of the Bowman's capsule and glomerular tuft were traced, and the number of grid points overlaying the glomerular tuft (P glom ) and the entire renal corpuscle (P corp ) were counted. Assuming glomerular sphericity, and that the cross section analysed provided the mean cross-sectional area, mean renal corpuscle volume (V corp ) and glomerular volume (V glom ) were then determined using the following Weibel and Gomez equation 23,36,39 :…”

“…The number of capillary profiles (traced lumens) within the glomerulus (Q-) and the number of times that the boundaries of the capillaries intersected with the horizontal and vertical lines of the orthogonal grid (I cap ) were counted. 23,36 Capillary length (mm) per glomerulus was then calculated by multiplying V glom (equation above) by the capillary length density per glomerulus (Lvcap, glom) 23,36 :…”