A subpopulation of hippocampal glial cells specific for the zinc-containing mossy fibre zone in man.

The projection of the zinc-containing axons of granule cells of the fascia dentata, e.g. the mossy fibres, is restricted to the hilar region and sector CA3 of the hippocampus. Serial sections of human hippocampi were stained for zinc-containing fibres with a non-perfusion Timm method, while adjacent ones were stained with Darrow red and aldehydefuchsin. GFAP, glutamine synthetase immunocytochemistry and a specific silver stain were employed to label other subtypes of astrocytes. The distribution of Timm-stained areas correlates only with the distribution of aldehydefuchsin-positive glial cells, most probably astrocytes. Since glial cells regulate axonal outgrowth in a region-specific manner, it is temptative to speculate that the aldehydefuchsin-positive glial cell is a candidate for a specific neuron-glia interaction which is somehow involved in the control of outgrowth of mossy fibres.