Synaptic conduction is mostly ohodromic because

Chemical mediator is located only in the presynaptic terminal An axon can conduct the impulse in either direction. When an action potential is initiated in the middle of an axon, 2 impulses traveling in opposite directions are set up by electronic depolarization on either side of the initial current sink. In living animals, impulses normally pass in one direction only Q (from synaptic junctions or receptors along axons to their termination). Such conduction is called ohodromic. Conduction in the opposite direction is called antidromic. Q Since synapses, unlike axons, permit conduction in 1 direction only, any antidromic impulse that they set up fail to pass the first synapse they encounter and die out at that point Ref: guyton and hall textbook of medical physiology 12 edition page number:675,676,677