The development of neuron-specific enolase (NSE) immunoreactivity in mouse sensory and ganglion vestibular cells was studied from gestation day 14 to adulthood. NSE staining appeared sequentially in these structures with a pattern that closely paralled their maturation sequences. The onset of NSE reactivity, at gestation day 15, in ganglion cells was concomitant with the formation of contacts between the afferent fibers and sensory cells, and was observed in hair cells, at gestation day 17, during the period in which the first synaptic structures form. The development of NSE staining in the cristae revealed an apex-base and axial gradients of maturation.
