In the rat hippocampus, extranuclear ERα-is found postsynaptically in dendritic spines and presynaptically in terminals, some of which are cholinergic. A. ERα-immunoreactivity (arrowhead) is found in a dendritic spine emanating from a dendritic shaft. The spine is contacted (curved arrow) by an unlabeled terminal. B. A terminal with ERα-immunoreactivity (arrowhead) also contains silver intensified immunogold (black particles) labeling the cholinergic marker, vesicular acetylcholine transporter (VAChT). A, B, CA1 Stratum radiatum. Bars, 500 nm.