The objective of this study was to explore the hypothesis that developing labyrinthine sensory receptors attract ingrowing neurites by chemotaxis. Cocultured otic explants which shared a single statoacoustic nerve (VIIIn) ganglion were explanted from 11-, 12.5-, and 14-day-old mouse embryos. Heterotypic ganglion explants consisted of 12-day-old otic explants which had their VIIIn replaced by a 10.5-day-old trigeminal nerve (Vn) ganglion. All cultures were grown to the equivalent of 20 days of gestation. Neurites of the (+) VIIIn explants grew into the sensory areas of both the (+) and (-) VIIIn cocultured explants. Neurites of the 14-day-old cocultured otic explants were only found in association with sensory areas within the (+) VIIIn explant. Neurites of nerve V of the heterotypic ganglion explants were found in association with the sensory areas of these otic explants. These results support the hypothesis that a limited period of chemotaxis (nonspecific in nature) is a possible mechanism for the establishment of the pattern of neurite ingrowth to the areas of the inner ear sensory receptors.
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