Fig. 4. Cs-Mesp is essential for specification of TVCs. (A-E) Expression of genes in TVCs of control and (A'-E') Cs-Mesp-MO1-injected embryos. (A,A') Cs-Nkx; (B,B') Cs-HAND; (C,C') NoTrlc; (D,D') a gene orthologous to the C. intestinalis ID00152 gene; and (E,E') ATP2A1/2/3. Inserts in (A,A',B,B') are ventral views of the trunk region showing Cs-Nkx and Cs-HAND expression. Arrows in (A-E) indicate TVCs. Red arrows in A'-E' indicate suppressed expression of downstream genes in TVCs. (F,F') Tailbud embryos in which the B7.5-lineage cells are labeled with DiI. (F) In a control embryo, TVCs (white arrow) and two anterior muscle cells (arrowheads) are labeled. (F') In a Cs-Mesp-MO1-injected embryo, labeled cells are not observed in the region in which TVCs should be located (a red arrow). Instead, four labeled cells are observed in the tail (arrowheads).