PMC

Diagram of the relative dominance of the basal over the apical leaf cushion field. Legend: Horizontal axis: Length apical leaf cushion field/ total length leaf cushion, vertical axis length basal leaf cushion field/ total length leaf cushion. Pink square: Lubná red cross: Mt Pelé, light green diamond: Ronchamp, dark green cross: Oelsnitz, dark blue star: St Etienne, purper circle: Kladno.

Example confocal fluorescent image quantifications from control embryos. (A) Phalloidin (red) stain fluorescence intensities from a full cushion, where the average fluorescent intensity at each distance position across the cushion is plotted. (B) Cushion cell density measured from the number of outlined DAPI-stained nuclei (blue) within an area 10 μm into the cushion from the lumen edge. (C) Cell count per endocardium length measured from the number of outlined DAPI-stained nuclei (blue) along with a measured length of the endocardium. (D) Periostin (red) front length measured as a percentage of the length of the full cushion. (E). VE-cadherin (red) junction per endocardium length measured from the number of outlined junctions along a measured length of the endocardium. Scale bar = 50 microns.

Schematic leaf cushion organisation: Total length and width leaf cushion, length apical and basal field leaf cushion, height and width leaf scar.

Hypoplastic defects in the IFT, atrium and AV cushion of the Smo mKO mutant embryos. (a–d3) Gross morphology and H&E staining of midsagittal sections of the control and Smo mKO mutant hearts at E8.75 showing the IFT (Ctrl: a,b,b1; Mut: c,d,d1), atrium (Ctrl: a,b,b1; Mut: c,d,d1) and AV cushion (Ctrl: b,b2; Mut: d,d2). b3 and d3 show cartoon illustrations of the cardiac anatomical structure in the control and mutant hearts at E8.75, respectively. (e–h3) Gross morphology and H&E staining of midsagittal sections of the control and Smo mKO mutant hearts at E9.5 showing the IFT (Ctrl: e,f,f1; Mut: g,h,h1), atrium (Ctrl: e,f,f1; Mut: g,h,h1) and AV cushion (Ctrl: f,f2; Mut: h,h2). f3 and h3 show cartoon illustrations of the cardiac anatomical structure in the control and mutant hearts at E9.5, respectively. The arrows in f2 indicate mesenchymal cells in the AV cushion. (i–j) Statistical comparison of the length of the dorsal myocardial wall from the base of the IFT to the junction between the ventricle and AV canal (i: E8.75; j: E9.5). (k–l) Sizes of the IFT and atrium relative to that of the right ventricle in the control and Smo mKO mutant embryos (k: E8.75; l: E9.5). Scale bars: 100 µm. The histogram shows the means ± SEMs.