Fig. 5. PGC cluster formation correlates with proper differentiation of the target tissue. (A,C,E,G,I,K) Flat-mounts of embryos at the six- to eight-somite stage stained for wt1 in blue. (B,D,F,H,J,L) Flat-mounts of embryos at the same stage stained with nos1 in blue to visualize the PGCs. The position of the main clusters of PGCs in the anterior trunk is marked by an arrow and that of the ectopic anterior clusters by an arrowhead. Embryos have been stained with other markers in red or blue for identification of mutants and for providing positional landmarks (see Materials and Methods). Note that wt1 is expressed at normal or only slightly reduced levels in all embryos that show clustering of PGCs in the anterior trunk (spt, oep and oep;ntl). (M-O) Lateral views of embryos at 24 hpf stained for nos1 in blue. The position of the main PGC clusters is marked by an arrow and that of the ectopic anterior cluster by an arrowhead. PGC main clusters have formed in the correct region at the anterior end of the yolk extension in wild-type (M) and spt (N), but not in spt;ntl (O) double mutants. Note the presence of PGCs in between the ectopic anterior and the main clustering positions in spt;ntl mutants (O).
