Olfactory marker protein is a cytoplasmic component unique to fully-differentiated olfactory sensory neurons. It has been proposed that expression of this protein occurs only if the neurons make synaptic contact with the central nervous system. In the present experiments, adult olfactory epithelium was transplanted as an autograft to the anterior chamber of the eye. This procedure destroys the mature sensory neurons, which are subsequently replaced by division and differentiation of stem cells. The newly-formed sensory neurons differentiate sufficiently to produce olfactory marker protein, without apparently contacting central nervous tissue. We conclude that contact with the central nervous system is not necessary for expression of olfactory marker protein.