False-colour transmission electron micrograph (TEM) of Leishmania sp.,a parasitic flagellate protozoan that causes the disease leishmaniasis in humans. The parasite assumes a different form in each of its two hosts,humans & the sandfly,its insect carrier. This example,from human tissue,appears as a small rounded structure,with no protruding flagellum,and is known as a Leishman- Donovan body. Here,the flagellum (outlined in orange) appears retracted. In its sandfly host,it takes on an elongated,motile (flagellate) form. Human infection affects cells of the lymphatic system,spleen & bone marrow. Magnification: x10,600 at 6x7cm,x5,300 at 35mm size |