Fig. 3. Impaired paraxial mesoderm production in lulu. (A-D) Expression of Tbx6 RNA in E8.5 wild-type (WT; A,C) and lulu (B,D) embryos, shown in whole mount (dorsal view in A, ventral in B) and transverse sections through the streak (C,D). (A,B) Tbx6 expression flanks the streak and node in wild type (A); this domain is reduced in lulu mutants (B). (C,D) Cells accumulate under the streak in lulu mutants, producing a bulge of Tbx6-negative cells (D, arrow). (E,F) Immunofluorescence on transverse sections through the streak at E8.5. E-cadherin (red) and Sox2 (green) are maintained in cells underlying the streak in lulu mutants (F, arrow), but are lost in cells exiting the streak in wild type (E, arrow). Anterior is to the left in A,B; dorsal is up in C-F. Scale bars: 50 µm in A,B; 30 µm in C-F.