title: Ultrastructure of the cellular elements of the "accessory" conduction system of the human embryonic and foetal heart.
mesh_terms: D004622:Embryo, Mammalian; D005318:Fetal Heart / Q000294:innervation*; D006329:Heart Conduction System / Q000166:cytology / Q000196:embryology* / Q000648:ultrastructure; D006801:Humans