Abstract
Ultrastructural localization of zinc in the hippocampus of rabbits and rats was investigated by the application of Timm's sulfide-silver and zinc-dithizonate methods. Best results were obtained by fixation of tissue in 3% glutaraldehyde saturated with H2S, followed by treatment of small blocks of tissue with Timm's solution for 1 hr. In sections cut from these blocks, silver particles were found on the synaptic vesicles in the terminal boutons of the mossy fibers. The nervous tissue of the hippocampal formation was devoid of silver particles, as were the perikarya of the granular cells of the fascia dentata and the pyramidal cells of the hippocampus. The cytochemical significance of zinc in nerve endings of the granular cells is discussed.