Single promastigote form Leishmania mexicana cell as seen by scanning electron microscopy. Promastigote form Leishmania mexicana (WHO strain MNYC/BZ/62/M379) were grown in M199 (10% FCS, pH 7.4, 28°C). Cells were fixed with 2.5% glutaraldehyde, dehydrated in an alcohol/water series then then critical-point dried and sputter coated with gold. Image captured on a JSM-6390 scanning electron microscope (JOEL).