Immunolocalization of Col1a1 in the pulmonary valve (green, A-B), aortic valve (C, E, F, G, H) and mitral valve (D, H) in hearts from 1.5 to 5 month old mice. Boxes highlight areas of ectopic muscle (blue, B, C, F, G). Solid arrows- valve anchor abnormalities; open arrows- ectopic valve leaflet-like extensions; PV- pulmonary valve; Ao- aorta; IVS- interventricular septum; TV- tricuspid valve. Red- propidium iodide (PI); blue- αSMA (A-D); αSarc (E-H). Scale bar: A= 400μm applies to B-H.