Synapse formation is related to the onset of neuron-specific enolase immunoreactivity in the avian auditory and vestibular systems.

Neuron-specific enolase (NSE) is a unique form of the glycolytic enzyme, enolase, which, in the brain, is strictly localized in differentiated neurons and neuroendocrine cells. In this report evidence is presented that NSE is first seen in the cell bodies of developing chick auditory and vestibular neurons shortly after the time when they first form immature synapses. Subsequently, immunoreactive NSE increases and spreads into transiently appearing structures which participate in the morphogenesis of mature synaptic arrangements. These data correlate synaptogenesis with the differentiation of a specific neuronal enzyme.