Figure 3.

Histograms showing the frequency of (a) aromatase-positive pre-synaptic boutons, (b) aromatase-positive somata and (c) total synapses in adult zebra finches (males are shown as black bars). Aromatase expressing synapses are observable in HVC, where aromatase-positive soma are non-detectable (ND). Further, the total number of synaptic profiles is higher in males compared to females overall in (c) as is the frequency of stained profiles in (a). ND=not detected. F values (and the degrees of freedom used in their computation) for the main effects and interaction are depicted.