subsequently , some of the identified cortical and thalamic target areas were injected with retrograde tracers such as wheat germ-agglutinin conjugated with horseradish peroxidase ( wga-hrp ) or with a fluorescent tracer -- fast blue or nuclear yellow -- in order to disclose the laminar origin of the parahippocampal efferent projections .
C0019941
horseradish peroxidase
C0078473
wga-hrp