Postnatal development of vestibular receptor surfaces in the rat.

The development of vestibular receptor surfaces was studied during the postnatal period in the rat on the 1st, 7th, 13th, 32nd and 75th days after birth. Cristae and utricles increase and change their shapes, up to day 13 for the cristae and day 32 for the utricles. Cristae hair bundles are less developed than those of the utricles on the 1st day after birth, with evidence of ciliogenesis being present in the cristae. There is an increase in hair bundle length in both organs that appears complete by the 32nd day after birth. These results are discussed in relation to the ultrastructural and electrophysiological studies concerning the postnatal maturation of the vestibular receptors.