Subpial neuronal migration in the medulla oblongata of Pax-6-deficient rats.
In rat fetuses, neurons generated in the lower rhombic lip on embryonic day 14 (E14) specifically express the transcription factor Pax-6 and migrate circumferentially in the subpial region along axons which are immunoreactive for TAG-1, a neural cell adhesion molecule. These neurons ultimately settle from E17 in the contralateral medulla oblongata to form the precerebellar nuclei, the lateral reticular and external cuneate nuclei. We have examined this migratory process in rat small eye (rSey2) which has a mutation in the Pax-6 gene. Both the migration and settlement of neurons labelled with 5-bromo-2'-deoxyuridine (BrdU) at E14 delayed in the mutant. Furthermore, in the ventrolateral part of the E16 mutant medulla oblongata, cells both expressing Pax-6 mRNA and prelabelled with BrdU at E14 were ectopically localized in the deep zone of the medullary parenchyma in addition to the normal subpial location. These ectopic neurons remained in close contact with ectopic TAG-1-immunoreactive axons. These results indicate that Pax-6 plays a role in the migration of medullary precerebellar neurons, although neurons generated in the lower rhombic lip can nevertheless migrate and settle to form the external cuneate nucleus in the absence of Pax-6.
Horie
Masao
M
Department of Developmental Morphology, Tokyo Metropolitan Institute for Neuroscience, Fuchu 183-8526, Japan.
Sango
Kazunori
K
Takeuchi
Kosei
K
Honma
Shizuka
S
Osumi
Noriko
N
Kawamura
Koki
K
Kawano
Hitoshi
H
D000818:Animals; D001369:Axons / Q000737:chemistry; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis; D002465:Cell Movement; D002531:Cerebellum / Q000254:growth & development; D058969:Contactin 2; D005136:Eye Proteins; D005455:Fluorescent Antibody Technique; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008526:Medulla Oblongata / Q000737:chemistry / Q000196:embryology / Q000254:growth & development*; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D010841:Pia Mater / Q000254:growth & development; D051381:Rats; D011922:Rats, Mutant Strains; D017207:Rats, Sprague-Dawley; D012097:Repressor Proteins
D015816:Cell Adhesion Molecules, Neuronal; C548676:Cntn2 protein, rat; D058969:Contactin 2; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605733:Pax6 protein, rat; D012097:Repressor Proteins