Neurons that migrate from the olfactory epithelium in the chick express luteinizing hormone-releasing hormone.

In several mammalian species, luteinizing hormone-releasing hormone (LHRH) neurons have been shown to migrate from nasal regions to the brain during early development. Using immunocytochemistry, we have identified LHRH containing neurons in developing chick embryos. In embryonic day 4 (E4) and E5 animals, a small group of LHRH immunoreactive (IR) neurons were found just ventral to the olfactory pit. LHRH-IR neurons were also found within the immunoreactive (IR) neurons were found just ventral to the olfactory pit. LHRH-IR neurons were also found within the nasal epithelium. In E6 and E7 animals, many more LHRH-IR neurons were observed in nasal epithelium, in close association with the olfactory nerve, and within the telencephalon. These data are consistent with the hypothesis that LHRH neurons in chicks originate within nasal structures and migrate into the brain.