1 Introduction.- 2 Materials and Methods.- 2.1 Tissue Preparation.- 2.1.1 Fixed Tissue.- 2.1.2 Unfixed Tissue.- 2.2 Immunocytochemistry.- 2.2.1 Primary Antisera.- 2.2.2 Specificity Controls for Primary Antisera.- 2.2.3 ICC Procedure for LM Single Labeling.- 2.2.4 ICC for LM Double Labeling.- 2.2.5 ICC for EM.- 2.2.6 Controls for Double Labeling.- 2.2.7 ICC for FM Single and Double Labeling.- 2.2.8 Controls for Fluorescence ICC.- 2.3 In Situ Hybridization.- 2.3.1 Probes.- 2.3.2 Hybridization Conditions.- 2.3.3 Posthybridization Washings.- 2.3.4 AP Detection.- 2.3.5 Probe Specificity Controls.- 2.3.6 ISH on Perfusion-Fixed Tissue.- 2.3.7 ISH on Unfixed Sections.- 3 Results and Discussions.- 3.1 Cytoarchitectonics.- 3.2 Comparative Light, Fluorescence, and Electron-Microscopic Studies of the Morphology and Neurochemistry of Catecholaminergic Afferent Fibers to the Amygdala.- 3.2.1 Introductory Remarks.- 3.2.2 Results.- 3.2.2.1 Distribution and LM Morphology.- 3.2.2.2 Colocalization of Enzyme-Immunoreactivities in Amygdala Axons.- 3.2.2.3 Colocalization of Enzyme-Immunoreactivities in Noradrenergic and Adrenergic Neurons Projecting to the Amygdala.- 3.2.2.4 Double Labeling for LM.- 3.2.2.5 Comparative Electron Microscopy.- 3.2.3 Conclusions for the Identification of Dopaminergic, Noradrenergic, and Adrenergic Structures.- 3.2.3.1 TH, DBH, and PNMT as Markers for Dopaminergic, Noradrenergic and Adrenergic Afferent Fibers of Certain Nuclei.- 3.2.3.2 Identification of Dopaminergic, Noradrenergic, and Adrenergic Afferent Fibers in Nuclei with Combined Innervation.- 3.3 Ultrastructural Features of Neurons and Catecholaminergic Afferent Fibers in the Nucleus Centralis, the Basal Complex, and the Paracapsular Intercalated Cell Groups.- 3.3.1 The Ultrastructure of Neuronal Perikarya.- 3.3.1.1 Central Nucleus.- 3.3.1.2 Basal Complex.- 3.3.1.3 Paracapsular Intercalated Cell Groups.- 3.3.2 Ultrastructural Features of Catecholaminergic Afferent Fibers and of Their Contacts with Tarló5