CALYCEAL SYNAPSE OF TYPE I VESTIBULAR HAIR CELLS

The type I vestibular hair cell, except as its apex, is entirely surrounded by a nerve calyx. In the basal region of the hair cell two distinct junctional complexes exist. In one, the intercellular space is wide (250-350 ) and contains finely granular material. Synaptic ribbons are distributed more or less randomly along this junction. In the other, fusion, or very close apposition, of membranes occurs. It is proposed that junctional complexes containing synaptic ribbons are chemical synapses and that the areas of membrane fusion are electrical synapses. Synaptic modifications are absent along the neck of the hair cell. © 1968 Academic Press Inc.