Figure 2: Developmental stages of Trypanosoma cruzi. (a) Amastigote, the nonflagellate intracellular morphologic stage; (b) epimastigote, long spindle-shaped hemoflagellate morphologic form equipped with a free flagellum and an undulating membrane that extends one half of the body length. It is found in the vectors responsible for transmitting the Trypanosoma species; (c) promastigote, characterized by a free anterior flagellum and the kinetoplast at the anterior end of the body; (d) trypomastigote, leaf-like form with an undulating membrane and often a free flagellum; (e) choanomastigote, barleycorn shaped with a collar-like process where the flagella emerges. Intracellular stage inside the invertebrate host; (f) opisthomastigote, no undulating membrane. Found in the invertebrate host only. (1) Nucleus, (2) kinetoplast, (3) basal body, (4) flagellar pocket (5) flagellum, (6) undulating membrane, (7) mitochondrion, and (8) subpellicular microtubules.