 RNA into the YSL of Mvg0 mutants. Whereas it has been previously shown that Nodal expression in YSL is sufficient to induce mesoderm and endoderm in the overlying blastoderm, this experiment would indicate that Cyc-Vg0 and Sqt-Vg0 heterodimers secreted from YSL are sufficient to create Nodal activity gradient to not only induce but also pattern the blastoderm. However, this experiment raises many questions: has injection been truly confined to the YSL (there is no lineage tracing data presented and a sceptic could argue that the 00 embryos that were rescued express the ligands also in the blastoderm due to ineffective injection? The evidence that expression is confined to the YSL is essential. It would be also important to show that Smad0 activity in such embryos parallels WT pattern shown by the authors in their earlier publications. It would be also important to show that the ligands targeted by RNA injection to the YSL can be seen in extracellular spaces in the blastoderm.  00\) How does the above result fit with the models of Nodal autoinduction and self-inhibition? In the model presented in [Figure 0](#fig0){ref-type="fig"} and in the Discussion, the authors see an important role of Sqt and Cyc expressed at the embryonic margin not just in the YSL.  