The Graham and Karnovsky Horseradish Peroxidase Ultrastructural Method: A Premier JHC Citation Classic

This commentary briefly reviews the background for the development of the horseradish peroxidase–diaminobenzidine tetrahydrochloride histochemical method originally described by Graham and Karnovsky in their citation classic, reprinted in full in this issue of Journal of Histochemistry & Cytochemistry. Some of the method’s subsequent applications, including its use as a macromolecular tracer for kidney glomerular permeability and use in immunoelectron microscopy and other immunoassays, are also discussed.