Expression of an epithelial membrane glycoprotein by neurons arising from the human olfactory plate through development.

Human terminal-vomeronasal neural crest cells began to express a 34,000 molecular weight epithelial membrane glycoprotein, which was detected by the mouse monoclonal antibody Ber-EP4 soon after their migration into the olfactory plate. Expression of this antigen continued in neurons arising from these cells, which were olfactory sensory neurons and luteinizing hormone-releasing hormone-producing neurons migrating into the brains of the embryos of approximately 44-52 postovulatory days. Ber-EP4 immunoreactivity appeared over the entire surface membranes of these neurons, including their processes, not only in their extracerebral portions, but also within the brain parenchyma from 48 to 53 postovulatory days. Ber-EP4 immunoreactivity of these migrating neurons became weaker as they matured into luteinizing hormone-releasing hormone-producing neurons and disappeared from the postnatal hypothalamic neurons; however, it remained in the primary sensory nerve fibers throughout postnatal life. Except for the neurons arising from the olfactory plate, no other human neurons express this epithelial antigen during the course of development. The mechanism and significance of the expression of this antigen in mature sensory neurons remains unclear, but the intramucosal location and morphological kinship of these neurons to epithelial cells may be related to this phenomenon. The results of the present study indicate that neurons arising from the olfactory plate are distinct from other neurons by having a 34,000 molecular weight epithelial membrane glycoprotein that can be detected by the mouse monoclonal antibody, Ber-EP4, during the embryonic stage. This antigen disappears from the luteinizing hormone-releasing hormone-producing neurons concomitant with maturation, but is preserved in the olfactory primary sensory nerve throughout postnatal life.