Transient architectonic features in the basolateral amygdala of the human fetal brain

The architectonical differentiation in the basolateral nuclei of the human fetal amygdala - with special reference to transient structures - was studi ed using series of relatively thick Nissl-stained sections. These architect onic features were correlated with the process of migration. Radial glial f ibers providing the scaffold of migratory routes can reliably be marked wit h the aid of antivimentin. In the 5th gestational month a transient feature is conspicuous in the inferior portions of the basolateral nuclei borderin g upon the ganglionic eminence (proliferative zone): columnar cell clusters , separated by cell-sparse septa, extend from the proliferative zone to the nuclei. The width of the cell columns vary considerably between the differ ent nuclei. In vimentin immunopreparations fibers are found inside these ce ll columns. So they most probably reflect clustered migratory streams. Two months later, instead of this merging area between the ganglionic eminence and the amygdaloid nuclei a cell-free capsule envelopes the nuclei and clea rly separates them from the ganglionic eminence. Changes in cytoarchitecton ics are accompanied by a distinct rearrangement of radial glial fibers. A b asket-like arrangement of the vimentin-immunoreactive fibers around the cel l columns inside the cell sparse septa is found. Towards the end of pregnan cy radial glial fibers gradually vanish. A comparison of Nissl and vimentin preparations reveals that transient architectonic characteristics as visib le in relatively thick Nissl sections may be correlated with migrational ro utes.