MM 2-10 is the abbreviation of our Membrane Marker 2-10, chemically called N-(3-triethylammoniumpropyl)-4-(4-(diethylamino)styryl)pyridinium dibromide. In literature this membrane marker is also called FM 2-10 (FM® is the trademark of Molecular Probes). It is a fluorescent membrane stain similar to MM 1-43, but slightly more hydrophilic. The release of MM 2-10 styryl dye is proportional to the time for which the synaptic vesicle is fused to the plasma membrane.