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 immunohist ochemical investigation of developmental changes in the distribution of cal bindin and calmodulin in the vestibular organ of the musk shrew (Suncus mur inus). Expression of calbindin was seen first in the hair cells and the ves tibular 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 immunor eactivity in hair cells similar to that seen in adults. The developmental d ifferences 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.