Figure 2.

wnt4a is expressed in early zebrafish gonads. Confocal images of isolated gonads stained for wnt4a mRNA (red), Vasa to label germ cells (green), nuclei (blue) (A–H), or wnt4a RNA only (A′–H′), and gonadal tissue outlined by a dotted line (A–C). (A and A′) At 10 dpf (n = 8) and (B and B′) 12 dpf (n = 9), wnt4a RNA was detected ubiquitously in germ cells (gc) and somatic cells (sc). (C and C′) In contrast, wnt4a RNA was not detected in gonadal cells at 14 dpf (n = 6). (D and D′) At 20 dpf, wnt4a RNA was detected in a small subset of somatic cells (n = 4). At 23 dpf (n = 10), wnt4a expression was detected in somatic cells both in presumptive ovaries (E and E′) and in gonads that are transitioning to testes, with cyst-like divisions to the right of the dashed line (F and F′). At 25 dpf, wnt4a mRNA was detected (G and G′) in the developing ovary (n = 6), (H and H′) but not in gonads that appeared to be transitioning to testes (n = 10). Bar, 20 µm.