1. Introduction.- 2. Outline of Synaptic Morphology.- 2.1. Synaptic Parameters.- 2.2. Synaptic Variation.- 3. Issues in Synaptic Terminal Organization.- 3.1. Vesicle-Membrane Relationships.- 3.2. Microfilamentous Network.- 3.3. Coated Vesicles.- 3.4. Protein Composition of the Junctional Region.- 3.5. Microtubular System.- 4. Models of the Presynaptic Terminal.- Summary.- References.