Proliferation of radial glia (RG) is increased in response to stab wound injury. Representative images of proliferative RG (BLBP⁺PCNA⁺ cells) in the uninjured (A) and injured (B) hemispheres at 2 days post injury (dpi). (A’,B’) Magnified images of the boxed area in (A,B). (C–F) Representative images of proliferative RG in the injured hemisphere at 6 h post injury (hpi) and at 1, 4, and 7 dpi. White arrowheads indicate BLBP⁺PCNA⁺ cells, and dashed lines indicate injured areas. Scale bar: 50 μm in (A–F) and (A’,B’). Schematic drawing of the stab injury in the right hemisphere of the optic tectum and cross-section. (G) Quantification of proliferative RG in both uninjured and injured hemispheres at 6 (n = 5) and 12 (n = 3) hpi, and 1 (n = 5), 2 (n = 5), 3 (n = 4), 4 (n = 5), and 7 (n = 4) dpi. (H) Quantification of proliferative cells (BLBP^–PCNA⁺ cells) except NE in both uninjured and injured hemispheres at 6 (n = 5) and 12 (n = 3) hpi, and 1 (n = 5), 2 (n = 5), 3 (n = 4), 4 (n = 5), and 7 (n = 4) dpi. Statistical analyses between uninjured and injured hemispheres at each time point were evaluated using paired Student’s t-tests. Statistical significance was defined as *P < 0.05; **P < 0.01; ***P < 0.001.

Generation of newborn neurons in the injured medaka is limited compared with zebrafish. (A) Schematic drawing of bromodeoxyuridine (BrdU)-labeling and stab injury in the right hemisphere of the optic tectum. Representative images of newborn neurons (BrdU⁺HuC⁺ cells) in both injured zebrafish (B) and medaka (C). White arrowheads indicate BrdU⁺HuC⁺ cells, and dashed lines indicate the injured areas. Scale bar: 50 μm. (D) Quantification of BrdU⁺HuC⁺ cells in the uninjured and injured hemispheres in zebrafish (n = 4) and medaka (n = 4). (E) Quantification of total BrdU⁺ cells in both uninjured and injured zebrafish (n = 4) and medaka (n = 4). Statistical analyses were evaluated using one-way analysis of variance followed by Tukey’s post hoc test. Statistical significance was defined as *P < 0.05.

Pro-regenerative transcriptional factors are differentially expressed between the injured medaka and zebrafish. Quantitative polymerase chain reaction analysis of the pro-regenerative transcriptional factors ascl1a (A), oct4 (B), sox2 (C), and stat3 (D). Graphs indicate the relative gene expression in the injured tectum from 6 to 168 h post injury (hpi) compared to the uninjured tectum (n = 4). Statistical analyses between the uninjured and injured hemispheres at each time point were evaluated by unpaired Student’s t-tests. We used * for zebrafish and ^† for medaka to indicate significant difference. Statistical significance was defined as * and ^†P < 0.05; ** and ^††P < 0.01; *** and ^†††P < 0.001.

Persistent glial scar-like structure is observed in the injured medaka tectum. (A–H) Representative images of immunostaining with anti-GFAP and anti-BLBP antibodies on the uninjured (A: zebrafish and B: medaka) and injured hemisphere at 7, 14, and 30 days post injury (dpi) [(B–D): zebrafish and (E–H): medaka]. (I–P) Magnified images of the boxed area at 14 dpi [(I–L): zebrafish and (M–P): medaka]. The dashed lines indicate the injured areas. Scale bar: 100 (A–H) and 50 (I,M) μm.