Figure 2.

Behavioral and morphological effects of cyclical estradiol treatment in aged female rhesus monkeys. A, Neuropsychological performance in aged OVX plus vehicle (OVX + VEH) and OVX plus estradiol (OVX + E) monkeys in DR (for details, see text), showing the mean percentage correct across delays of 5–60 s. Note enhanced performance of OVX + E group at all delays (Rapp et al., 2003a). B, Histogram showing quantitative data on spine density (spine number per micrometer of dendritic length) in layer III pyramidal neurons from area 46. Note that the OVX + E group has significantly higher spine density in both apical and basal dendritic arbors and throughout all branch orders in the apical tree. C, High-resolution examples of apical and basal dendritic segments from a filled neuron from both OVX + E- and OVX + VEH-treated monkeys. Scale bar, 5 μm. **p < 0.01. Error bars indicate SEM.