Figure 3.

Nkx2.5^Cre/+; Hand1^A126FS/+ E12.5 mutants present with an elongation of the cardiac OFT. (A) Nkx2.5^+/+; Hand1^SF-A126FS/+ wholemount control compared with two Nkx2.5^Cre/+; Hand1A^126FS/+ mutants (F, K). Measure of cardiac OFT (white bars) shows that mutant OFTs extend farther into the forming RV, which appears smaller and shows some signs oedema (white arrowhead). Section analysis of the control shown in (A). (B–E) reveals expected structural development that includes a septated pulmonary trunk (pt) developing IVS and LV. Magnification in (E) shows a well-formed compact zone (black bar). Matched sections from Nkx2.5^+/+; Hand1A^126FS/+ mutants shown in (F) and (K). (G–O) A poorly formed IVS (asterisk), small RV, and a thinner compact zone (J, O). Size of the LV is indistinguishable between control and Nkx2.5^+/+; Hand1A^126FS/+ mutant hearts. Data represent an example of each genotype. Ten embryos per genotype were examined. ra, right atria; la, left atria; rv, right ventricle; lv, left ventricle; ivs, intraventricular septum; pt, pulmonary trunk. Scale bars 150 and 500 μm.