The architectural development of the early mammalian heart.
D000818:Animals; D004699:Endocardium / Q000648:ultrastructure; D006321:Heart / Q000196:embryology*; D006325:Heart Atria / Q000648:ultrastructure; D006352:Heart Ventricles / Q000648:ultrastructure; D051379:Mice; D008854:Microscopy, Electron; D009206:Myocardium / Q000648:ultrastructure; D009210:Myofibrils / Q000648:ultrastructure