Fig. 4. Mesonephric defects in Gata3^-/- embryos. Pax2 expression was detected in wild-type (A,C,E) or Gata3^-/- (B,D,F) embryos at 17 somites (A,B), 21 somites (C,D) and 27 somites (E,F). (A-D) A delay is observed in the caudal extension of Pax2⁺ mesonephric cells (broken red lines in B,D,F) of Gata3^-/- embryos. (E,F). The distinct Pax2 expression domains in the nephric cord and duct of wild-type embryos (insert in E) were replaced by a single stream of Pax2⁺ cells (black arrowheads, insert in F) with regions of discontinuity (white arrowheads) in Gata3^-/- embryos. ms, mesonephros; mst, mesonephric tubules; nc, nephric cord; nd, nephric duct.