Development of the Vestibular System

This review mainly focuses on the development of the vestibular system in humans and other mammals, but reference is made to anurans and other species where applicable. In the first section, the steps involved in the development of undifferentiated cells into mature vestibular receptors are analysed. Available data indicate that in humans, maturation of the vestibular receptor and its afferent innervations involves a similar sequence of events as in other mammalian species. In the second section, morphological and physiological aspects of the maturation of the central vestibular system are presented. Undifferentiated neuron precursors have been identified in specific segregrated domains of the hindbrain neural tube, and these can develop into secondary vestibular neurons with unique properties. Several neuronal populations in the vestibulospinal and vestibulo-ocular pathways have been found to correlate with rhombomeric domains at early embryonic stages. In rodents, the vestibular system continues to develop postnatally in terms of morphology and function until it achieves its final form. The postnatal changes in the properties of vestibular nuclear neurons are chronologically matched with structural changes and serve to prime the development of vestibular-induced reflexes. Copyright © 2002 S. Karger AG, Basel The time course of the maturation of hair cells and their afferent innervation patterns in the vestibular system has been fully documented in histological and ultrastructural studies in a number of animal species, such as rats [1, 2] and mice [3–9], as well as in humans [10]. Comparison of different maturational events in humans and other animals is of particular interest. Through these correlations, it is possible to extrapolate from experimental results in animals to predict what may occur in the human vestibular system. Development of the Peripheral Vestibular