Altered myelinated fiber trajectory at various postnatal days in the cerebral cortex of reeler mice by immunohistochemical stain with MBP antiserum.

The cerebral cortex of reeler mutant mice characterized by the derangement of cell position was analyzed by an immunohistochemical staining technique using antiserum against myelin basic protein. All the myelins of the myelinated fibers were stained, so that the fiber trajectories could be clearly traced. In the present study the changes in the fiber trajectories were accompanied by changes in myelination sites. Myelinated fibers were localized in the central white matter and gradually became sparser toward the surface of the normal cerebral cortex, while in the reeler myelinated fibers were observed throughout the cortical plane. From the immunohistochemical analysis of the changes occurring in the myelinated fiber pathways in developmental sequence, it was also shown that the fiber bundle accumulation was thin at the earlier stages (e.g. the 15th postnatal day) and became thick as the animal grew, and the timing of myelination in the reeler was similar to that of the control.