A combined silver and cholinesterase method for studying exact relations between the pre- and the postsynaptic elements at the frog neuromuscular junction.

Combination of Karnovsky's cholinesterase staining with silver impregnation of axons (modified Bodian's technique) offers a new means of studying the relation between the pre- and postsynaptic elements in the frog neuromuscular junction. The method can be applied to whole muscles so that synapses of individual superficial muscle fibers which have previously been investigated by electrophysiological techniques can be identified after staining. In this way synaptic activity can be correlated with such synaptic features as number of axon branches, length of the occupied synaptic gutter, axonal sprouts, etc. The distinction between occupied and unoccupied parts of the synaptic gutters is useful when studying reinnervation, regression, or growth of a synapse.