Scanning electron microscopic observation of the foetal labyrinthine vestibule.

Vestibular portions of three foetal inner ears were examined by scanning electron microscope. The sensory cells from a 14-week foetus showed a coexistence of hair bundles of different lengths, indicating that the sensory cells were still in the developing stage. An 18-week foetus showed more developed hair bundles. A distinct kinocilium and unidirectional polarization of sensory cells were clearly seen even in the young short hair bundles. In all foetuses examined, non-sensory ciliated cells were found located on the vestibular wall between the utricular macula and all three cristae ampullares. These ciliated cells seem to disappear with maturation because these cells were not found in other postnatal inner ear specimens examined by the same method.