<i>In situ</i> hybridization for Bad mRNA in the RA, LMAN, HVC and Area X of the Bengalese finch.

<p>A1–D2: Labeled cells in the RA at post-hatching day (P) 45 (A1, A2), the LMAN at P35 (B1, B2), the HVC at P45 (C1, C2), and in Area X at P35 (D1, D2). E-H: Comparisons of the densities of Bad mRNA-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C2 and 300 μm in D1–D2. The data are expressed as the mean ± SEM.</p

Immunohistochemistry for Bax in the RA, LMAN, HVC and Area X of the Bengalese finch.

<p>A1–D4: Labeled cells are observed in the RA at post-hatching day (P) 35 (A1, A2) and in the adult (A3–A4), in the LMAN at P15 (B1, B2) and in the adult (B3, B4), in the HVC at P35 (C1, C2) and in the adult (C3, C4), and in Area X at P15 (D1, D2) and P45 (D3, D4). E-H: Comparison of the densities of Bax-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 and D4 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C4 and 300 μm in D1–D4. The data are expressed as the mean ± SEM. *<i>P</i>< 0.05.</p

Immunohistochemistry for TrkB in the RA, LMAN, HVC and Area X in the Bengalese finch.

<p>A1–D2: Labeled cells in the RA at post-hatching day (P) 15 (A1, A2), the LMAN at P25 (B1, B2), the HVC at P15 (C1, C2), and in Area X at P45 (D1, D2). E-H: Comparisons of the densities of TrkB-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C2 and 300 μm in D1–D2. The data are expressed as the mean ± SEM. *<i>P</i>< 0.05, **<i>P</i>< 0.01.</p

Immunohistochemistry for BDNF in the RA, LMAN, HVC and Area X of the Bengalese finch.

<p>A1–D2: Labeled cells in the RA at post-hatching day (P) 25 (A1, A2), the LMAN at P45 (B1, B2), the HVC at P15 (C1, C2) and in Area X at P35 (D1, D2). E-H: Comparisons of the densities of BDNF-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (the dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C2 and 300 μm in D1–D2. The data are expressed as the mean ± SEM. *<i>P</i>< 0.05, **<i>P</i>< 0.01.</p

Immunohistochemistry for caspase-3 in the RA, LMAN, HVC and Area X in the Bengalese finch.

<p>A1–D4: Labeled cells are observed in the RA (A1–A4), LMAN (B1–B4), HVC (C1–C4) and Area X (D1–D4) in males at post-hatching days P15 (A1–D1) and P45 (A3–D3) and in females at P15 (A2–D2) and P45 (A4–D4). E-H: Comparison of the densities of caspase-3-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to identify clearly, and the dashed lines in D2 and D4 indicate the approximate region that corresponds to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C4 and 300 μm in D1–D4. The data are expressed as the mean ± SEM. **<i>P</i>< 0.01.</p

<i>In situ</i> hybridization for Bcl-2 mRNA in the RA, LMAN, HVC and Area X in the Bengalese finch.

<p>A1–D2: Labeled cells in the RA at post-hatching day (P) 45 (A1, A2), the LMAN at P35 (B1, B2), the HVC at P35 (C1, C2), and in Area X at P35 (D1, D2). E-H: Comparisons of the densities of Bcl-2 mRNA-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C2 and 300 μm in D1–D2. The data are expressed as the mean ± SEM. **<i>P</i>< 0.01.</p

Nissl-defined volumetric changes of song control nuclei in the Bengalese finch from post-hatching day (P) 15 to 120.

<p>A: RA; B: LMAN; C: HVC; D: Area X; m: male; f: female. The mark “#” indicates that significant sexual differences are present in the marked groups towards adulthood. As the Nissl-defined borders of the female Area X in all studied age groups were difficult to clearly identify, the volume of the female Area X is not available in D.</p

TUNEL labeling in the RA, LMAN, HVC and Area X of the Bengalese finch at post-hatching day (P) 45.

<p>A-K: Positive cells in RA (A, B), LMAN (D, E), HVC (G, H) and Area X (J, K). Comparison of the densities of TUNEL-positive cells between males and females in the RA (C), LMAN (F), HVC (I) and Area X (L). High magnification views of the labeled cells are shown in the insets (J, K). Scale bars = 400 μm in J and K and 200 μm in the other panels. The borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined borders of the female Area X were difficult to clearly identify, and the dashed lines in K indicate the approximate region that corresponds to the male Area X. The data are expressed as the mean ± SEM. *<i>P</i>< 0.05.</p

Immunohistochemistry for Bcl-xL in the RA, LMAN, HVC and Area X of the Bengalese finch (visualized by nickel intensified DAB).

<p>A1–D4: Labeled cells in the RA at post-hatching day (P) 35 (A1, A2) and P45 (A3–A4), in the LMAN at P15 (B1, B2) and P45 (B3, B4), in the HVC at P45 (C1, C2) and in the adult (C3, C4), and in Area X at P15 (D1, D2) and P45 (D3, D4). E-H: Comparison of the densities of Bcl-xL-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. The borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 and D4 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C4 and 300 μm in D1–D4. The data are expressed as the mean ± SEM. *<i>P</i>< 0.05, **<i>P</i>< 0.01.</p

<i>In situ</i> hybridization for Bid mRNA in the RA, LMAN, HVC and Area X of the Bengalese finch.

<p>A1–D2: Labeled cells in the RA at post-hatching day (P) 45 (A1, A2), the LMAN at P45 (B1, B2), the HVC at P35 (C1, C2), and in Area X at P15 (D1, D2). E-H: Comparisons of the densities of Bid mRNA-positive cells in the RA (E), LMAN (F), HVC (G) and Area X (H) between males and females. Borders of the song nuclei (dashed lines) were determined with the help of another set of Nissl-stained sections. The Nissl-defined border of the female Area X was difficult to clearly identify, and the dashed lines in D2 indicate the approximate region corresponding to the male Area X. Dorsal is up and caudal is right. Scale bar = 200 μm in A1–C2 and 300 μm in D1–D2. The data are expressed as the mean ± SEM. **<i>P</i>< 0.01.</p