Journal of Neuroscience, Vol 3, 2197-2205, Copyright © 1983 by Society for Neuroscience
Olfactory bulb increases marker protein in olfactory receptor cells
MI Chuah and AI Farbman
Olfactory mucosa was excised from the heads of embryonic day 15 (E15) rat
fetuses, prior to the appearance of olfactory marker protein (OMP), and
cultured with or without the presumptive olfactory bulb. Specific
immunohistochemical staining for the OMP was detected in both groups of
explants 6 days after explantation. At no time do the supporting cells and
basal cells show positive OMP staining. Results of radioimmunoassay on the
two groups of cultures showed that about twice as much OMP was present in
organ cultures grown with presumptive olfactory bulb. Estimates of the area
of olfactory mucosa in the explants revealed no significant differences
between those cultured with or without the bulb. Cell counts revealed that
the increased amount of OMP in explants with the bulb was due to a higher
number of OMP-positive receptor neurons. Explants of olfactory mucosa
cultured with other tissues (cerebrum, cerebellum, cervical spinal cord,
and heart) contained approximately the same amount of OMP as explants of
mucosa alone; i.e., these other tissues did not enhance OMP levels.
Similarly, there was no enhancement of OMP level when the olfactory mucosa
was separated from the bulb by a Millipore filter of 0.45 micron pore size.
Thus the results of the study indicate that the presumptive olfactory bulb
specifically increases OMP level by a mechanism that requires direct
contact between the receptor cells and bulb.