Calbindin and calmodulin localization in the developing vestibular organ of the musk shrew (Suncus murinus)

The distribution of the Ca²⁺-binding proteins, calbindin and calmodulin, in the adult inner ear has been described previously. We undertook immunohistochemical investigation of developmental changes in the distribution of calbindin and calmodulin in the vestibular organ of the musk shrew (Suncus murinus). Expression of calbindin was seen first in the hair cells and the vestibular ganglion on gestational day (GD) 19, in nerve fibres on GD23 and in the otoconia on GD26. On GD19 calmodulin was demonstrable only in the hair cells. On GD26 both Ca²⁺-binding proteins showed a distribution of immunoreactivity in hair cells similar to that seen in adults. The developmental differences in distribution of these binding proteins may suggest different roles in the vestibule. Additionally, Ca²⁺-binding proteins may be a useful index of hair cell maturity.