Fig. 5. Steroidogenic cells migrate from the anterior region of the mesonephros into the Wnt4^-/- XX gonad. Gonads from Wnt4^-/- XX 11.5-12.5 dpc embryos were incubated with mesonephroi from Cyp11a1:lacZ 11.5-12.5 dpc embryos and stained for ß-galactosidase activity. (Top) The anterior region of the mesonephros was included in the co-culture, and (bottom) the anterior region of the mesonephros was removed. The lines indicate the boundary between gonad and mesonephros in the co-cultures.