Straying phenomenon of migrating LHRH neurons and highly polysialylated NCAM in the chick embryo

Enzymatic removal of polysialic acid from neural cell adhesion molecule perturbs the migration route of luteinizing hormone-releasing hormone neurons in the developing chick forebrain

“…PSA-NCAM immunoreactivity was present both in migrating LHRH neurons and in the developing olfactory nerve, and SST immunoreactivity also was detectable in the olfactory nerve and its associated fibers (Figs. 2, 3), as reported in our previous studies (Murakami et al, 1991(Murakami et al, , 1995Murakami and Arai, 1994b). Coexpression of SST and PSA-NCAM was confirmed by double staining for SST and PSA-NCAM in these olfactory fibers.…”

“…Similarly, in the chick embryo, several reports have described the migration pathway of LHRH neurons through the nasal septum along the olfactory nerve to the forebrain (Murakami et al, 1991;Norgren and Lehman, 1991;Sullivan and Silverman, 1993). Consistent with this mechanism, either physical interruption of the central projection of olfactory nerve or placodectomy induces a failure of LHRH neurons to migrate from the nasal region to the brain (Akutsu et al, 1992;Murakami et al, 1995Murakami et al, , 1998.…”

LHRH neuronal migration: heterotypic transplantation analysis of guidance cues

“…In the Rhesus macaque, a few LHRH neurons were found in the optic nerve (Witkin, 1987). In the chick, LHRH neurons have been observed within a ophthalmic branch of the trigeminal nerve after the olfactory placode was damaged (Murakami et al, 1995). However, the olfactory nerve was contiguous with the trigeminal nerve and could not be distinguished from it with the methods employed by these authors.…”

Netrin 1 provides a chemoattractive cue for the ventral migration of GnRH neurons in the chick forebrain

“…GnRH neurons relocate along axons outside the brain (Murakami et al, 1995;Murakami and Arai, 2002). A subset of olfactory fibers that express neural cell adhesion molecule (NCAM), PSA, or somatostatin extend along the medial surface in the chick telencephalon (Norgren and Brackenbury, 1993;Murakami and Arai, 1994b;Murakami et al, 2000).…”

“…In various vertebrates, septohypothalamic GnRH neurons originate from the olfactory placode and migrate along the olfactory, terminal, and/or vomeronasal nerves to reach the forebrain, and then finally, the hypothalamus during embryogenesis Wray et al, 1989;Muske and Moore, 1990;Ronnekleiv and Resko, 1990;Murakami et al, 1991;Sullivan and Silverman, 1993;Parhar et al, 1995). Experimental studies (Murakami et al, 1995;Murakami and Arai, 2002) and a report on Kallmann syndrome showed that the migrational pattern of GnRH neurons is principally axondependent outside the brain. Once GnRH neurons enter the forebrain, most of them migrate tangentially along a subset of olfactory fibers that take a caudal trajectory (Norgren and Brakenbury, 1993;Murakami and Arai, 1994b;Wray et al, 1994;Yoshida et al, 1995), suggesting a type of axophilic migration.…”