Light microscopic visualisation of the presynaptic nerve terminal calyx in dissociated chick ciliary ganglion neurons.

The pre- and postsynaptic elements of the calyx-type synapse in the chick ciliary ganglion were stained with Lucifer yellow in situ, and the structure of this synapse was examined after enzymatic dissociation of the ganglion. Back-staining of the ciliary nerve resulted in darkly stained neuronal cell bodies. Foreward-staining of the presynaptic oculomotor nerve did not stain the neurons, but instead resulted in a 'halo' of fluorescence around the cell bodies, corresponding to the large presynaptic calyxes. This study demonstrates the feasability of staining the presynaptic terminals in dissociated ciliary neurons and demonstrates the range of calyx structure at this physiologically interesting synapse.