a) Conversion of 3H-DHEA into 3H-AE (left) and 3H-estrogens (right) by homogenates of the adult zebra finch telencephalon. The 3β-HSD inhibitor trilostane abolished 3H-AE production (left); the aromatase inhibitor Fadrozole decreased 3H-estrogen production by 97% (right; from Soma et al., 2004); b) Caudal view of a 300μm thick parasagittal slice of an adult male zebra finch telencephalon containing two song system motor nuclei: robust nucleus of the arcopallium (RA, thick arrow) and HVC (thin arrow). Note the tract that runs from HVC to RA; c) Incubation of male telencephalic slices with 200nM 3H-DHEA for 10, 30, and 90 mins in the presence or absence of the 3βHSD inhibitor trilostane. Tritiated estrogens and 5α-androstanedione (5α-A) were isolated and quantified: ▲, estrogens; Δ, estrogens + trilo; ■, 5αA; □, 5αA + trilo (from Tam and Schlinger, 2007).