title: Ultrastructural differentiation of the cellular elements of the internodal connections of the human embryonic and foetal heart.
mesh_terms: D001283:Atrioventricular Node / Q000196:embryology / Q000648:ultrastructure; D002454:Cell Differentiation; D005318:Fetal Heart / Q000648:ultrastructure*; D006321:Heart / Q000196:embryology*; D006801:Humans; D009206:Myocardium / Q000648:ultrastructure; D012849:Sinoatrial Node / Q000196:embryology / Q000648:ultrastructure