Sex difference in cellular proliferation within the telencephalic ventricle zone of Bengalese tinch

Cellular proliferation within the ventricular zone (VZ) may contribute to sex differences through the net addition of neurons in song control nuclei. To address this issue, we administered [H-3]thymidine to Bengalese finches of both sexes, and estradiol benzoate (EB) to females 15 days post hatching. The birds were killed 2 h later to examine thymidine labeled cells within the VZ at three brain levels, HVC, anterior commissure and Area X. Our results indicated that: (1) cell proliferation in the VZ was significantly higher in the three studied brain levels in males and EB implant females relative to intact or empty implant females, respectively; (2) proliferation in the dorsal half of the VZ, in proximity to HVC, was notably higher than that in the ventral half of the VZ; (3) proliferation in the ventral VZ (VVZ), which is relatively close to Area X was higher relative to other subregions of VZ (dorsal and intermediate). Our study suggests that sex differences in cell proliferation in the VZ may contribute to the net growth of HVC and Area X in males, and estradiol may play an important role in sexual difference in cellular proliferation within the VZ. (c) 2007 Published by Elsevier Ireland Ltd and the Japan Neuroscience Society.