title: Lanthanum as an electron microscopic stain.
abstract: Applications of lanthanum as an electron microscopic tracer have been reviewed. This electron-dense trivalent cation, which binds avidly to calcium binding sites, can be used as tracer for delineating extracellular spaces and intercellular junctions. It has served as a basis for classification of junctional structures. It can also be used as a calcium probe, a tracer in studying the permeability of barriers, as an intracellular marker and as an electron microscopic stain for such membrane components as surface glycoprotein. Each of these applications may require a different methodology. Thus methodological considerations in the use of this tracer have also been reviewed. The recent recognition that lanthanum is more than a passive tracer and that by reacting with different cell components may serve as a true stain, will extend the use of lanthanum in electron microscope histochemistry.
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000032:analysis; D002462:Cell Membrane / Q000032:analysis; D002463:Cell Membrane Permeability; D011232:Chemical Precipitation; D003102:Colloids; D005110:Extracellular Space; D005614:Freeze Fracturing; D006651:Histocytochemistry; D007365:Intercellular Junctions / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000032:analysis; D007811:Lanthanum; D008854:Microscopy, Electron; D009940:Organoids / Q000032:analysis / Q000648:ultrastructure; D010539:Permeability; D010743:Phospholipids / Q000032:analysis; D013194:Staining and Labeling
chemical_list: D002135:Calcium-Binding Proteins; D003102:Colloids; D010743:Phospholipids; D007811:Lanthanum