Figure 3.

BDNF immunostaining of the male zebra finch HVc at different ages. A 20-day-old male already has many BDNF-containing neurons within HVc (Upper Left). At 45 days, staining specifically within HVc is very pronounced to both the cells and neuropil (Upper Right). Also seen at this age are several stained axon bundles that connect HVc to RA (arrows). A 65-day-old bird still shows heavy BDNF staining, but the labeling is largely confined to the neuropil (Lower Left). An adult bird shows little BDNF labeling (Lower Right). (Bar = 200 μm.)