TrkA expression in olfactory epithelium and bulb during development.

The purpose of the present study was to examine immunohistochemically the expression of high-affinity nerve growth factor receptor (trkA) in the olfactory nervous system of developing mice and of colchicine-treated adult mice. Olfactory epithelia of embryos and neonates showed trkA immunoreactivity not only in basal cells but in receptor cells, with trkA-immunoreactive olfactory nerve fibers in the subepithelium and the bulb. In adults, trkA immunoreactivity was found only in basal cells of olfactory epithelia. Olfactory epithelia of colchicine-treated adult mice, however, exhibited appearance of trkA-immunoreactive receptor cells and increased trkA immunoreactivity in olfactory nerve fibers. These findings indicate that expression of trkA continually occurs in the olfactory nervous system during life and that trkA can be highly expressed during development.