Calcitonin gene-related peptide in the developing mouse olfactory system.

The development of calcitonin gene-related peptide (CGRP) was investigated in the mouse olfactory system. The peptide was not found in olfactory receptor neurons in embryos examined from gestational day 13 (E13) to E18 but was present in other brain regions and in peripheral tissues. At E18, CGRP-immunoreactive fibers, presumably of trigeminal, not olfactory receptor cell, origin were observed within the lamina propria. These data suggest that in vivo CGRP does not act through olfactory receptor neurons to regulate phenotypic expression in the olfactory bulb.