Modified Nauta and Fink-Heimer procedures with special reference to the demonstration of monoaminergic pathways in the central nervous system.

Modifications of the selective silver impregnation methods of Nauta and Fink-Heimer are described. Both procedures were tested in wide variety of species: from reptiles to carnivores, as well as in human autoptic cases. The modified Nauta procedure is recommended as a method of choice for tracing axonal trajectories due to an improved impregnation selectivity of the degenerating axoplasm.