FIGURE 12-25 Hormonal Effects A comparison of the dendrites of hippocampal pyramidal neurons at high and low levels of estrogen in the rat’s (4-day) estrous cycle reveals far fewer dendritic spines in the low period.

Information from C. S. Woolley, E. Gould, M. Frankfurt, & B. McEwen (1990). Naturally occurring fluctuation in dendritic spine density on adult hippocampal pyramidal neurons. Journal of Neuroscience, 10, p. 1289.