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Overview

SEM Pathology

Table of contents

1. Examination of common tissue samples

Staining properties of platinum blue

Staining properties of osmium tetroxide

2. Examination of renal biopsy samples

3. Advantages of LVSEMs and future tasks

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(3) Comparison of platinum-blue and PAM staining images (high-magnification images)　#100004

Cross-sectional LVSEM images of glomeruli (Platinum-blue staining, PAM staining)

Figure No.100004a

Staining: Platinum-blue staining

Microscope: LVSEM
Sample: Paraffin section (IgA nephropathy)

Accelerating voltage: 15 kV

Magnification: ×4,000

P: Podocytes (Epithelial cells)　E: Vascular endothelial cells　M: Mesangial cells　GBM: Glomerular basement membranes　MM: Mesangial matrix　Bs: Bowman's space

Image description
LVSEM image5) of a glomerulus from a patient with IgA nephropathy stained with platinum blue. Podocytes (epithelial cells, P) and vascular endothelial cells (E) are stained positive with platinum blue and are the brightest in the image. Mesangial cells (M) are slightly darker than these cells. The glomerular basement membranes (GBM: arrows) and mesangial matrix (MM) are negative with platinum blue and appear dark in the image. These differences in staining specificity allow the unambiguous identification of each glomerular component. Inset: The thickness of the GBM (determined using the measurement mode of the SEM).

Figure No.100004b

Staining: PAM staining

Microscope: LVSEM
Sample: Paraffin section (Membranous glomerulonephritis)

Accelerating voltage: 15 kV

Magnification: ×7,000

P: Podocytes (Epithelial cells)　E: Vascular endothelial cells　M: Mesangial cells　GBM: Glomerular basement membranes　MM: Mesangial matrix　L: Capillary lumen　Bs: Bowman's space

Image description
LVSEM image 5) of a glomerulus from a patient with membranous glomerulonephritis stained with PAM. The glomerular basement membranes (GBM: arrows) and mesangial matrix (MM) are stained positive with PAM and are visualized as bright and distinct structures. The basement membranes show spike formation that is characteristic of membranous glomerulonephritis. Podocytes (epithelial cells, P) that line the outer surface of the glomerular capillaries, vascular endothelial cells (E), immune substances, and mesangial cells (M) are negative with PAM and thus appear dark and undefined in the image.

Characteristic findings

When paraffin sections of renal glomeruli are stained with platinum blue or PAM, their basic structures show differences in brightness as indicated below. This produces a light-dark contrast between neighboring structures in LVSEM images.

＜Platinum-blue staining＞

  • Positive (Bright): Podocytes (epithelial cells), vascular endothelial cells, mesangial cells, blood cells, and others.
  • Negative (Dark): Basement membranes, mesangial matrix, collagen fibers, and others.

＜PAM staining＞

  • Positive (Bright): Basement membranes, mesangial matrix, collagen fibers, and others.
  • Negative (Dark): Podocytes (epithelial cells), vascular endothelial cells, mesangial cells, blood cells, immune substances, and others.

Observations

In images of platinum blue-stained samples, we can detect disease-specific morphological alterations of podocytes and mesangial regions (cells and matrix). In contrast, PAM staining reveals different features, including the structural changes of basement membranes and the expansion of mesangial matrix.

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