title: Birth-date-dependent segregation of the mouse cerebral cortical neurons in reaggregation cultures.
abstract: Cerebral cortical neurons form a six-layered structure in which their position depends on their birth date. This developmental process requires the presence of Reelin, which is secreted by Cajal-Retzius cells in the cortical marginal zone (MZ). However, it is still unclear whether the migration from the ventricular zone (VZ) to beneath the MZ is essential for the neurons to segregate into layers. Previous transplantation studies of ferret cerebral cortical neurons suggested that their ultimate laminar fate is, at least to some extent, determined in the VZ but it is unknown how 'laminar fate' eventually positions cells in a specific layer. To explore the segregation properties of mouse cortical cells that have not yet arrived beneath the MZ, embryonic day (E)16 VZ and intermediate zone (IMZ) cells were dissociated and allowed to reaggregate for 1-4 days in vitro. The results suggested that the migrating neurons in the IMZ at E16 preferentially located near the centre of the aggregates, more than did the proliferative cells from the VZ. The birth-date labelling followed by the dissociation-reaggregation culture suggested that the segregation properties of the E16 IMZ was characteristic of the E14-born cells, which were migrating in the IMZ at E16, but they were not general properties of migrating IMZ cells. This birth-date-dependent segregation mechanism was also observed in the Reelin signalling-deficient yotari cells. These findings suggest that cortical neurons acquire a birth-date-dependent segregation mechanism before their somas reach the MZ.
authors.affiliation: Department of Anatomy, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Itsuki
authors.initials: I
authors.lastname: Ajioka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakajima
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D001973:Bromodeoxyuridine / Q000378:metabolism; D064026:Calbindins; D002448:Cell Adhesion / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000172:deficiency; D002449:Cell Aggregation / Q000502:physiology; D002452:Cell Count / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D048429:Cell Size; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D002552:Cerebral Ventricles / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D004622:Embryo, Mammalian; D016326:Extracellular Matrix Proteins / Q000172:deficiency; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000378:metabolism; D064231:Nestin; D009474:Neurons / Q000145:classification / Q000502:physiology*; D051857:Otx Transcription Factors; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D036121:Receptor, EphA3 / Q000378:metabolism; D000091042:Reelin Protein; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D012697:Serine Endopeptidases / Q000172:deficiency; D014404:Tubulin / Q000378:metabolism
chemical_list: D064026:Calbindins; D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D005904:Glial Fibrillary Acidic Protein; D018398:Homeodomain Proteins; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins; C079240:Mtap2 protein, mouse; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D051857:Otx Transcription Factors; D018809:Proliferating Cell Nuclear Antigen; D000091042:Reelin Protein; D064030:S100 Calcium Binding Protein G; D014404:Tubulin; C462941:beta3 tubulin, mouse; D049452:Green Fluorescent Proteins; D036121:Receptor, EphA3; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases; D001973:Bromodeoxyuridine