Differentiation and maturation of the sensory hair bundles in the fetal and postnatal vestibular receptors of the mouse: a scanning electron microscopy study.

By means of scanning electron microscopy, the differentiation and maturation of sensory hair bundles have been studied in the ampullar cristae of the mouse during development from gestational day 13 (GD13) to postnatal day 10 (PD10). Two gradients of ciliary differentiation were demonstrated, one from the apex to the base and the other from the center to the periphery. The different hair bundles that appeared on the crista during the fetal period originated in an initial ciliary stage found in regions undergoing differentiation, differentiation, which was visible at the apex of the crista starting on GD14. This stage of ciliary development is gradually followed by a juvenile one at GD15. Starting on GD18, the maturation of hair bundles in the central apical area differed from that in the peripheral areas and prefigured the regional specialization of the crista found in the adult stage. In the discussion, we suggest that when the vestibular epithelial cells begin to exhibit ciliary differentiation, they are simultaneously contacted by nerve fibers.