Morphology

T. cruzi has three morphological forms: the tyrpomastigote, the epimastigote, and the amastigote. Trypanosomes are present in the circulating blood. They are approximately 20 mm long and generally slender. They have a thin, irregularly shaped membrane, which can be seen using scanning electron microscopy. They have a centrally positioned nucleus, and a kinetoplast located towards the posterior. A flagellum stems from the kinetoplast and runs through the remainder of the parasite and also extends beyond it. Inside the kinetoplast is the parasite has single mitochondrion, which drive the flagellum. (de Souza, W. A Short Review on the Morphology of T. cruzi: from 1909-1999. Mem Inst Oswaldo Cruz, 94(1):17-36;1999.)

Cartoon of trypomastigote form of T. cruzi
http://images.google.com/imgres?imgurl=www.tulane.edu/~wiser/protozoology/notes/images/tc_lc_lg.gif&imgrefurl=

When visualized in Giemsa stained blood films, trypanosomes generally are seen in a C or U shape.

T. cruzi in trypomastigote stage
http://images.google.com/imgres?imgurl=www.tulane.edu/~wiser/protozoology/notes/images/tc_lc_lg.gif&imgrefurl=

The epimastigote is similar to the trypomastigote, but the kinetoplast is located anterior to the nucleus.

T. cruzi in the epimastigote stage
ttp://www.ucm.es/info/parasito/Epimastigotes.jpg

Amastigotes, on the other hand, are present within cells. They are generally round and the flagellum becomes nearly unapparent.(www.ucm.es/info/parasito/ aTLAS.htm)

T. cruzi in the amastigote stage

http://www.pasteur.fr/recherche/unites/tcruzi/minoprio/tropical/chagas/chapter3.html

In summary, here are simplified cartoons of the three morphological stages: trypomastigote, epimastigote, and amastigote, respectively.

http://images.google.com/imgres?imgurl=www.tulane.edu/~wiser/protozoology/notes/images/tc_lc_lg.gif&imgrefurl=