Both type I and II germ cells are eliminated by apoptosis in the <i>sox9b</i> mutant medaka.

<p>(A–H) Ventral views of 10 dph medaka gonads immunostained with anti-OLVAS (germ cell marker, purple) and anti-cleaved caspase 3 (blue). Merged images (A, C, E and G) and cleaved caspase 3 signals (B, D, F and H) are shown. Low levels of germ cell apoptosis only were evident in wild-type XY and XX medaka at 10 dph. However, type I and type II germ cells (type I, arrows; type II, a bracket) were eliminated by apoptosis (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029982#pone-0029982-t002" target="_blank">Table 2</a>) in the homozygous (E and F) and heterozygous (G and H) mutants. Scale bar, 50 µm.