The superficial layers of the superior colliculus are cytoarchitectually and myeloarchitectually disorganized in the reelin-deficient mouse, reeler.
The causative gene for the reeler mouse is reelin which encodes Reelin protein, an extracellular molecule. In the present study, we have examined the cytoarchitecture, myeloarchitecture, and afferent/efferent systems of the superior colliculus (SC) of the reeler mouse. In the reeler, the laminar structures of the superficial three layers of the SC were disorganized and intermingled into a single layer, i.e., the superficial fused layer (SuF), as previously reported in the reelin-deficient SRK rat (Sakakibara et al., Develop. Brain Res. 141:1-13). Next, we have investigated the course and terminals of visual corticotectal and retinotectal projections with an injection of biocytin into the visual cortex or an injection of cholera toxin subunit B into the retina, respectively. In the reeler, anterogradely labeled visual corticotectal and retinotectal fibers took an aberrant course within the SuF, resulting in abnormal myeloarchitecture of the superficial SC of the reeler. Retrograde labeling of tectospinal tract neurons could not show any differences between the normal and reeler mice, suggesting that the deep layers of the reeler SC are cytoarchitectually normal. In situ hybridization and immunohistochemical studies have shown that reelin mRNA and Reelin protein were both recognized in the normal SC. These results suggest that Reelin protein plays some roles in histogenesis of the superficial layers of the SC.
Baba
Kousuke
K
Department of Anatomy and Developmental Neurobiology, Kobe University Graduate School of Medicine, Kobe, Japan.
Sakakibara
Shunsuke
S
Setsu
Tomiyoshi
T
Terashima
Toshio
T
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism; D004525:Efferent Pathways / Q000378:metabolism / Q000648:ultrastructure; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D017403:In Situ Hybridization / Q000379:methods; D008239:Lysine / Q000031:analogs & derivatives / Q000378:metabolism; D051379:Mice; D008818:Mice, Neurologic Mutants / Q000033:anatomy & histology*; D004676:Myelin Basic Protein / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D000091042:Reelin Protein; D012160:Retina / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D013477:Superior Colliculi / Q000378:metabolism* / Q000648:ultrastructure*; D014793:Visual Cortex / Q000378:metabolism; D014795:Visual Pathways / Q000378:metabolism / Q000648:ultrastructure
D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins; D000091042:Reelin Protein; C000717129:Reln protein, rat; D002772:Cholera Toxin; D006735:Horseradish Peroxidase; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases; C013411:biocytin; D008239:Lysine