Figure 2

Differentiating gonad of Atlantic cod, presumptive male. Transverse plastic section (2 μm) stained with Toluidine blue/Borax solution. a) and a’) Undifferentiated gonad in a 14 mm TL juvenile; b) Early testis in a 18 mm juvenile (scale bar represents 10 μ); c) Early testis in a 34 mm juvenile (scale bar represents 10 μm); d) Testis of a 32 mm juvenile (scale bar represents 25 μm). BV – blood vessel; arrows indicate primordial germ cells.