Rationale: Authors used pre-embedding immunogold EM to study the cellular and subcellular localization of HAP1 in rat brain. They used a polyclonal antibody generated against the amino acids 287–452 from rat HAP1. Electron micrographs show immunogold particles distributed among, and often on the cytoplasmic surface of synaptic vesicles in axon terminals as well as in postsynaptic dendritic spines.. Experimental description: From M&M: Rabbit polyclonal antibodies specific for HAP1 were raised against a recombinant protein derived from a segment of the rat HAP1 (amino acids 287–452) fused to glutathione-S-transferase (GST) and affinity purified, as described previously (Li et al., 1995). Adult male Sprague Dawley rats (n=6) were used for light microscopic immunocytochemistry. Five additional rats were used for both immunoperoxidase and pre- embedding immunogold electron microscopy experiments.