Eck agreed, stating that it was "the best of the three non-chamber matches".
A variety of chamber and non-chamber specific genes have been characterized.
The myocardium fated to become non-chamber myocardium expresses a different set of molecular markers.
The analysis of the expression patterns of chamber and non-chamber markers in Tbx3 mutant embryos advocates that the initial specification of non-chamber myocardium occurs normally in these embryos.
Hallmarks of this remodeling are the looping of the heart tube and the regionalization into chamber and non-chamber myocardium.
In Tbx3 null mutant embryos, both TGFβ2 and Smad6 were downregulated in the non-chamber myocardium (Fig. 5L O).
Thus, the specification and differentiation of non-chamber myocardium is not altered in the presence of ectopic Tbx3 or Tbx2 in the heart tube.
Together these results show that the initial specification of chamber and non-chamber myocardium occurs in single and double morphants, but further development is impaired.
Consequently, the non-chamber myocardium forms constrictions in the heart tube, such as the AVC, that prevent backflow of blood before valve formation.
Bmp2 and Tgfβ2 are expressed in the OFT, AVC and IFT since early looping stages and are important for further development of the non-chamber myocardium [7], [8].
Loss- and gain-of-function analyses demonstrate that tbx3b and tbx2a are necessary to repress the chamber-genetic program in the non-chamber myocardium.
