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Updated: Oct 16, 2025
Assessment of Kidney Function in Mouse Models of Glomerular Disease
Published on: June 30, 2018
Evaluation of ultrastructural alterations of glomerular basement membrane and podocytes in glomeruli by low-vacuum
Ping Lan1,2, Dedong Kang1, Akiko Mii3
1Department of Analytic Human Pathology, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan.
Background:
Low-vacuum scanning electron microscopy (LV-SEM) is applied to diagnostic renal pathology.
Methods:
To demonstrate the usefulness of LV-SEM and to clarify the optimal conditions of pathology samples, we investigated the alterations of glomerular basement membrane (GBM) and podocytes in control and experimental active Heymann nephritis (AHN) rats by LV-SEM.
Results:
On week 15 following induction of AHN, spike formation on GBM with diffuse deposition of IgG and C3 developed. Using LV-SEM, diffuse crater-like protrusions were clearly noted three-dimensionally (3D) on surface of GBM in the same specimens of light microscopy (LM) and immunofluorescence (IF) studies only after removal coverslips or further adding periodic acid-silver methenamine (PAM) staining. These 3D ultrastructural findings of GBM surface could be detected in PAM-stained specimens by LV-SEM, although true GBM surface findings could not be obtained in acellular glomeruli, because some subepithelial deposits remained on surface of GBM. Adequate thickness was 1.5-5 μm for 10% formalin-fixed paraffin-embedded (FFPE) and 5-10 μm for the unfixed frozen sections. The foot processes and their effacement of podocytes could be observed by LV-SEM using 10%FFPE specimens with platinum blue (Pt-blue) staining or double staining of PAM and Pt-blue. These findings were obtained more large areas in 2.5% glutaraldehyde-fixed paraffin-embedded (2.5%GFPE) specimens.
Conclusion:
Our findings suggest that LV-SEM is a useful assessment tool for evaluating the alterations of GBM and podocytes in renal pathology using routine LM and IF specimens, as well as 2.5%GFPE specimens.
Insights
Low-vacuum scanning electron microscopy (LV-SEM) offers a valuable 3D view of glomerular basement membrane and podocyte alterations in renal pathology. Optimal sample preparation is key for clear visualization of these critical kidney structures.
Area of Science:
- Nephrology
- Pathology
- Electron Microscopy
Background:
- Low-vacuum scanning electron microscopy (LV-SEM) is increasingly applied in diagnostic renal pathology.
- Understanding its utility requires investigating optimal conditions for examining kidney tissue samples.
Purpose of the Study:
- To demonstrate the diagnostic utility of LV-SEM in renal pathology.
- To identify optimal sample preparation techniques for LV-SEM analysis of glomerular basement membrane (GBM) and podocytes.
Main Methods:
- LV-SEM was used to examine GBM and podocyte alterations in control and active Heymann nephritis (AHN) rat models.
- Specimens included routine light microscopy (LM), immunofluorescence (IF), and specialized staining (PAM, Pt-blue) on various fixed and unfixed tissues.
- Optimized section thicknesses for formalin-fixed paraffin-embedded (FFPE) and frozen sections were determined.
Main Results:
- LV-SEM revealed three-dimensional (3D) crater-like protrusions on the GBM surface in AHN rats, correlating with LM and IF findings.
- Periodic acid-silver methenamine (PAM) staining enhanced GBM surface visualization, though acellular glomeruli required careful interpretation.
- Podocyte foot process effacement was clearly observed in Pt-blue stained FFPE and 2.5% glutaraldehyde-fixed paraffin-embedded (2.5%GFPE) specimens.
Conclusions:
- LV-SEM is a useful tool for assessing GBM and podocyte alterations in renal pathology.
- The technique provides valuable 3D ultrastructural insights when applied to routine and specifically prepared specimens.
- Optimized fixation and staining protocols, particularly with 2.5%GFPE, improve visualization quality.
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