title: Subcortically and callosally projecting neurons are distinct neuronal pools in the motor cortex of the reeler mouse.
abstract: Subcortically projecting neurons and callosally projecting ones are distinct neuronal pools in the cerebral cortex of the rodents. However, cortical  efferent neurons are known to project multiple targets transiently by plural collateral axons. These plural axons are eliminated during prenatal and postnatal  development. In the cerebral cortex of the Reelin-deficient mouse, reeler, which is caused by mutation of the reelin gene, cortical efferent neurons are  ectopically distributed. However, it is still unknown whether cortical efferent neurons in the reeler mouse lose surplus collateral axons or maintain them  during developmental periods. If surplus collaterals of malpositioned cortical neurons are not eliminated, neurons projecting subcortically may project their  axons to the contralateral hemisphere. To test this plausible hypothesis, we made double injections of two fluorescent dyes, Fast Blue and Diamidino yellow  dihydrochloride into two of three regions, i.e., upper cervical cord, ventral lateral thalamic nucleus, and contralateral motor cortex of the normal and  reeler mice, to label corticospinal, corticothalamic and callosal commissure neurons in the motor cortex, retrogradely. No double labeled neurons were  identified in the motor cortex of the normal and reeler mice, although the distribution patterns of these cortical efferent neurons were completely  different between normal and reeler mice. These findings strongly suggest that collateral elimination of cortical efferent neurons during developing  periods are not affected in this mutant mouse.
authors.affiliation: Division of Anatomy and Developmental Neurobiology, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Imai
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Yu
authors.initials: Y
authors.lastname: Katsuyama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kikkawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Terashima
mesh_terms: D000578:Amidines; D000818:Animals; D005260:Female; D005456:Fluorescent Dyes; D007267:Injections; D008297:Male; D051379:Mice; D008818:Mice, Neurologic Mutants; D009044:Motor Cortex / Q000166:cytology*; D009474:Neurons / Q000166:cytology*; D000091042:Reelin Protein; D013116:Spinal Cord / Q000166:cytology*; D013788:Thalamus
chemical_list: D000578:Amidines; D005456:Fluorescent Dyes; D000091042:Reelin Protein; C031455:diamidino compound 253-50; C037945:diamidino yellow; C000717128:Reln protein, mouse