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. Author manuscript; available in PMC: 2009 May 1.
Published in final edited form as: Dev Biol. 2008 Feb 29;317(1):282–295. doi: 10.1016/j.ydbio.2008.02.037

Figure 1. Twist1 and Tbx20 are coordinately expressed with cell migration marker genes in endocardial cushions and remodeling valves.

Figure 1

Expression of Twist1, Tbx20, Cad11, Postn, and Mmp2 was examined in sectioned HH stage 25 and HH stage 36 chicken hearts. In situ hybridizations show Twist1 (A), Tbx20 (C), Cad11 (E), and Mmp2 (I) are expressed throughout the entire endocardial cushion. In addition, Twist1, Tbx20, and Cad11 expression was also detected in early epicardially derived cells (arrowheads in panel A, C, and E). In contrast, Postn was more strongly expressed in the ventricular aspect of the cushion near the intreventricular septum (arrow in panel G) and is absent from the subatrial region of the cushion (star in panel G). In remodeling mitral valves, Twist1 (B), Tbx20 (D), and Mmp2 (J) are expressed weakly throughout the entire valve leaflet and in epicardially derived cells (asterisks in panels B, D, and J). In contrast, Cad11 expression is weak and restricted to the distal tips of the valve (arrow in panel F) but is also expressed in the epicardially derived cells (asterisk in panel F). Postn is expressed at the intersection of the valve leaflet and the myocardium (arrow in panel H) with increased expression in the chordae tendineae and the papillary muscle points of insertion (arrowhead in panel H). In contrast, Postn expression is absent in epicardially derived cells (asterisk in panel H). EC, endocardial cushion; MV, mitral valve; IVS, interventricular septum; AS, atrial septum.