A SUBSET OF PERIPHERIN POSITIVE OLFACTORY AXONS DELINEATES THE LUTEINIZING-HORMONE-RELEASING HORMONE NEURONAL MIGRATORY PATHWAY IN DEVELOPING MOUSE

Luteinizing hormone releasing hormone (LHRH) neurons in the CNS are de rived from cells of the olfactory placode and thereafter migrate from the olfactory pit into the diencephalon. In this study, we examined em bryonic LHRH neurons and the LHRH migratory pathway for several marker s. During development, N-CAM and peripherin mRNA were expressed by olf actory epithelia, but not by LHRH cells. In nasal regions, olfactory a xons were not immunostained by laminin or fibronectin antibodies, but were robustly peripherin and N-CAM immunoreactive. Although the majori ty of these axonal tracks entered the developing olfactory bulbs, a sm all population of peripherin positive but N-CAM negative axons turned caudally into the developing forebrain. LHRH cells were consistently j uxtaposed to these axons. We propose that this peripherin positive/N-C AM negative fiber track is the anatomical pathway upon which LHRH cell s migrate from the olfactory pit into the diencephalon. (C) 1994 Acade mic Press, Inc.