Fig. 2

id1 and id2a expression in neural progenitors. A to L: PCNA (blue) and S100β (green) immunohistochemistry in the telencephalon of transgenic Tg(id1:EGFP) fish (GFP artificially put in red). Id1 transgene is expressed in type 1 (S100β-positive and PCNA-negative) and in type 2 (S100β and PCNA-positive) radial glial cells. E to H: high magnification views of the upper white box in D corresponding to the Dm region. Id1 transgene is strongly expressed in type 1 cells (arrows) and weakly or not by type 2 cells (arrowhead). I to L: high magnification views of the lower white box in D corresponding to the rostral migratory stream like region (RMS) region. Type 3 progenitors (S100β-negative and PCNA-positive) of the RMS do not express id1 (asterisks). M to X: id2a in situ hybridization (red) followed by PCNA (blue) and S100β (green) immunohistochemistry in the telencephalon. Id2a mRNA appears to be widely expressed in the telencephalon, in the parenchyma and the ventricular layer. Q to T: high magnification views of the upper white box in P corresponding to the Dm region. The arrows show an example of a type 1 progenitors (S100β and PCNA-negative) expressing id2a, while the arrowhead shows a type 2 progenitor (S100β-positive and PCNA-positive) exhibiting id2a expression. U to X: high magnification views of the lower white box in P corresponding to the RMS region. The asterisk shows an example of a type 3 progenitor (S100 β -negative and PCNA-positive) of the rostral migratory stream like region (RMS), expressing id2a transcripts. Scale bar: 8 µm (Q to T); 12 µm (I to L); 20 µm (U to X); 25 µm (E to H); 250 µm (A to D); 310 µm (M to P).