Expression of midkine in the cochlea.

Midkine (MK) is one of a new family of heparin-binding growth factors involved in the regulation of growth and differentiation. We have analyzed expression of MK in the cochlea using ICR mice within 1 day from birth. The expression of MK in the cochlea was confirmed by Western blotting and immunohistochemistry. Anti-MK immunoreactivity was observed in the stria vascularis, spiral prominence, spiral ganglion, and ganglion nerve fibers. These findings suggest that MK plays a role in the development of the cochlea.