title: Ultrastructural studies of the hearts in Arenicola marina L. (Annelida: Polychaeta).
mesh_terms: D000818:Animals; D000845:Annelida / Q000033:anatomy & histology*; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D003896:Desmosomes / Q000648:ultrastructure; D004847:Epithelial Cells; D004848:Epithelium / Q000648:ultrastructure; D006321:Heart / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D009206:Myocardium / Q000648:ultrastructure*; D009210:Myofibrils / Q000648:ultrastructure; D012508:Sarcolemma / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure