Fig. 6.

Decreased expression of extracellular matrix markers characteristic of valvulogenesis in HH35 OFT-banded hearts.

A. Decreased and a more diffuse staining of fibrillin-2 (arrow in b) in the primordial MV septal leaflet compared to controls (a). A similar reduction of type III collagen expression was also seen in the septal leaflet (arrow in d) and the chordae tendinae (arrow in f) in OFT-banded compared to controls (c and e, respectively) (n = 5).

B. Positive expression of fibrillin-2 (a), type III collagen (c) and tenascin (e) in the endocardial cushion (denoted by an arrow) seen in the controls was decreased in banded hearts (arrow in b, d and f respectively; asterix denotes ventricular septal defect). Arrowhead in c and d denote equivalent region of the endocardial cushion between controls and banded hearts (n = 5).

C. The fluorescence signal intensity of the primordial mitral valve leaflet was semi-quantified using MetaExpress software, with a significant reduction of fluorescence intensity for type III collagen (two-tailed Student's t-test; P < 0.05; n = 5). Scale bar in Aa 120 μm; same magnification for all panels in A&B.

D. qPCR showed a 1.06- and 1.26 downregulation of fibrillin 2 and tenascin C in HH35 banded hearts. A significant decrease was seen in type III collagen and TGM2 by 1.32 and 1.85 fold, respectively (two-tailed Student's t-test; P < 0.01; n = 3). Data represent means ± sem.

AS, atrial septum; AVJ; average grey level. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; VS, ventricular septum.