Basic Glomerular Histopathology

Overview
  • Diagnosis of glomerular diseases requires the use of a variety of histpathological techniques. These analytical tools, their uses and their limitations, are described below.
Light Microscopy
  • Technique
    • Sections stained with traditional dyes such as H&E can be visualized with light microscopy. These techniques are the normal workhorse of most histopathological analysis.
  • Uses
    • Light microscopy can reveal changes in the architecture of glomeruli along with the proliferation of glomerular cells or the presence of inflammatory cells.
  • Limitations
    • Light microscopy cannot determine the presence or absence of deposited antibodies or complement proteins which are often the initiators of glomerular injury in certain diseases.
Immunofluorescence
  • Technique
    • Immunofluorescence involves staining of histological sections with fluorescent agents that can specifically bind to particular proteins. These agents are then visualized using specialized fluorescent microscopes.
  • Uses
    • Immunofluorescence can be used to determine whether particular proteins are present within the histological section. Therefore, the presence of particular subtypes of antibodies or complement proteins can be determined using this technique. Furthermore, the pattern of immunoglombulin distribution within the glomerulus can suggest but does not formally prove what the immunoglobulin is targeting. For example, granular distributions of immunoglobulins suggest their presence in immune complexes whereas a ribbon-like pattern suggests that immunoglobulins are binding to antigens normally present within the glomerular basement membrane.
Electron Microscopy
  • Technique
    • Electron microscopy uses beams of electrons which are absorbed by "electron dense" structures such as subcellular processes and complexes of protein.
  • Uses
    • Electron Microscopy can be used to determine highly nuanced disturbances in the subcellular architecture of glomerular components that cannot be visualized with other types of microscopy. The status of the podocyte foot processes and the presence of actual electron-dense immune complexes can be formally detected with electron microscopy.