This review provides an update on the variety of histochemical techniques available for the cellular localization and expression of nitric oxide synthase in formalin-fixed tissue sections. The techniques of immunohistochemistry and NADPH-diaphorase histochemistry are discussed and the suitability of various types of probes and reporters which are useful for in situ detection of nitric oxide synthase mRNA expression are assessed. Figures are also included which illustrate the techniques described and protocols for in situ hybridization and NADPH-diaphorase histochemistry
