Fig. 3

Wild-type morphogenesis of AV valve leaflets. (A,B) Confocal images of the AV canal at 7 dpf. (C) Schematic drawing of a transverse section through the ventricle at the level of a valve leaflet. (D,E) Hematoxylin and Eosin-stained sections through the AV canal at 28 dpf. (F) Adult valve leaflets. (A,B) Sections of a Tg(Tie2:EGFP)^s849 (pseudo-colored blue) heart immunostained for Dm-grasp (pseudo-colored green) and stained with rhodamine phalloidin (red). (A) Optical section through the lateral wall of the ventricle as indicated in C shows that each of the two leaflets is connected to distal ventricular myocardial trabeculae (arrowheads). White parallelogram indicates the plane schematically depicted in C. (B) Optical section through the ventricle as indicated in C. Valve leaflets consist of two layers of Tg(Tie2:EGFP)^s849 positive cells (arrowheads). The myocardial wall distal to the AV canal is trabeculated in contrast to the juxtavalvular ventricular wall. The superior valve leaflet (arrow) is connected to the AV myocardium by a row of weakly Tg(Tie2:EGFP)^s849-positive (i.e. endocardially derived) cuboidal cells that express Dm-grasp (arrow). (C) Lines labeled A and B represent the approximate latitude of the optical sections shown in A and B, respectively. (D) Oblique section through the AV canal shows that the valve leaflets (arrowheads) are connected laterally to the ventricular trabeculae. (E) Sagittal section through the heart shows that the valve leaflets consist of two layers of cells (arrowheads). (F) The adult zebrafish AV valve consists of four leaflets (arrowheads). A, atrium; V, ventricle; sup, superior AV valve leaflets.