Zinc-enriched (ZEN) terminals in mouse spinal cord: immunohistochemistry and autometallography

The general distribution of zinc-enriched (ZEN) terminals in mouse spinal cord was investigated at light microscopic level by means of zinc transporter-3 immunohistochemistry (ZnT3(IHC)) and zinc selenium autometallography (ZnSe(AMG)). Staining for ZnT3(IHC) corresponded closely to the ZnSe(AMG) staining. Both appeared as dense grains of variable sizes and densities in the gray matter with a characteristic segmental laminar pattern. The white matter was unstained but contained rows of stained terminals radiating from the gray matter. In the dorsal horn, laminae I, III and IV were heavily stained, whereas lamina II appeared as the least stained area in the gray matter. Moderate staining was seen in laminae V and VI. In the ventral horn, large ZnT3(IHC) and ZnSe(AMG) grains, known from previous papers to represent ZEN terminals, were observed related in particular to motor neuronal somata and big dendrites. These ZEN terminals in the ventral horn were in general larger than those in the dorsal horn. This is the first description of the pattern of ZEN terminals in mouse spinal cord.