Bilaminar structure of the developing stapedial footplate in the mouse--a histological study using a light microscope.

Normal development of the stapes, especially the bilaminar structure of the footplate, in the mouse was investigated histologically. On day 14 of pregnancy, the footplate had an easily distinguishable lamina consisting of two layers. This bilaminar structure was seen clearly as a pale and loose portion composed of mesenchymal cells in the vestibular side adjacent to the original footplate in the stapedial ring. The authors considered this structure to be the same structure as the lamina stapedialis in the developing human stapes. A dualistic theory of the developmental origin of the footplate in the mouse is proposed.