FM1–84, FM1–43, SynaptoGreen C3 and FM2–10 share identical fluorophore cores. All of the FM dyes have two lipophilic ‘tails’; in FM1–84, the lipophilic tails are composed of 4 methylene groups and a terminal methyl group. FM1–43, SynaptoGreen C3, and FM 2–10 have hydrocarbon tails composed of 4, 3, and 2 carbons, respectively. FM 4–64 and FM 5–95 have the same two-carbon tails but have distinct charged ‘head’ regions.