The in vitro development of innervated sensory hair cells of a mammal.

Twelfth gestation day mouse embryo otocysts with their associated statoacoustic ganglions and otic mesenchyme were explanted to "in vitro". The otocyst explants developed for seven days in organ culture. They were then fixed and studied on a light microscopic and ultrastructural level for the development of synapses. Evidence is presented that strongly suggests that afferent synapses are developing "in vitro" in the vestibular sensory epithelium studied.