Journal of Neuroscience, Vol 13, 3018-3033, Copyright © 1993 by Society for Neuroscience
Lectin identification of olfactory receptor neuron subclasses with segregated central projections
DR Riddle, LD Wong and B Oakley
Neuroscience Program, University of Michigan, Ann Arbor 48109.
Our previous studies have demonstrated that the primary olfactory
projection in rainbow trout is organized nontopographically; the pattern of
termination of olfactory axons in the olfactory bulb is unrelated to the
distribution of their cell bodies in the olfactory mucosa. In the present
research we have further characterized the organization of this projection
by examining the lectin-binding properties of olfactory receptor neurons.
The results indicate that in trout, as in mammals, populations of olfactory
receptor neurons differ significantly from one another in their
carbohydrate "signatures." We have identified subsets of olfactory receptor
neurons, specified by unique lectin-binding properties, that are widely
distributed and intermingled with the other receptor neurons in the
olfactory mucosa and nerve, but that segregate as they enter the olfactory
bulb and project to restricted regions of the glomerular layer. This
pattern of terminations is bilaterally symmetrical, is remarkably
consistent across individuals, and reappears when the primary olfactory
projection is reconstituted following transection of the olfactory nerve.
As revealed by the carbohydrates on subpopulations of receptor neurons,
there is substantial order in the nontopographic projection of olfactory
receptor neurons to the olfactory bulb. The functional significance of this
organization and the means by which it develops and is maintained remain
under investigation.