Due to a publisher's error, the article entitled “Estradiol Mediates Fluctuation in Hippocampal Synapse Density during the Estrous Cycle in the Adult Rat” (C.S. Woolley and B.S. McEwen; J Neurosci 12:2549–2554, July 1992) was printed with an incorrect formula for a “conventional” method for calculation of synapse density. The formula should read as follows:
est Nv = N/(corr A x d)