A quantitative histochemical technique for the study of vascularization in tissue sections using horseradish peroxidase

Abstract

The use of horseradish peroxidase (mol. wt. 40 OOOd and diameter 4 nm) injected intravenously as a tracer to study transport at an ultrastructural level was introduced by Graham & Karnovksy (1966) for analysing the early stages of absorption in the proximal tubules of mouse kidney. This method, which employs 3,3-diam inobenzidine as an oxidizable substrate to reveal the injected peroxidase, is highly sensitive and affords a sharp Iocalization of small amounts of the enzyme. The method has subsequently been used to study vascular transport at an ultrastructural level in other organs and tissues such as cardjac and skeletal muscle (Karnovsky, 1967; Williams & Wissig, 1975), the alveolar-capillary membrane (Keeley & Karnovksy, 1968), liver (Graham et al., 1969) and lung (Clementi, 1970; Maisin, 1970; Schneeberger & Karnovsky, 1971).