Axonal projection of olfactory sensory neurons during the developmental and regeneration processes

We have studied the projection of olfactory sensory neurons (OSNs), during the developmental and regeneration processes, using the transgenic mouse ca rrying the differently tagged odorant receptor genes, MOR28. We have found that the axon terminals of the two sets of MOR28-positive OSNs, one express ing the lacZ tag and the other expressing the green fluorescent protein gen e, are dispersed and intermingled at early developmental or regeneration st ages. Projection areas become more distinct and separated at later stages, however, two sets of axon fibers are not typically bundled or segregated du ring pathfinding. It appears that segregation of axons mainly occurs when t hey target at the olfactory bulb to form the glomerular structure. NeuroRep ort 12:1061-1066 (C) 2001 Lippincott Williams & Wilkins.