Monday, August 26, 2013

Answer to Case 271

Answer:  Trypanosoma brucei trypomastigotes in peripheral blood.

Trypanosoma brucei is only present in humans as trypomastigotes (motile stages with flagella) in blood, unlike the other human trypanosome, T. cruzi, which can form both trypomastigotes AND non-motile tissue amastigotes in humans.  As noted by Anon and Florida Fan, the trypomastigotes of Trypanosoma brucei divide by binary fission in the peripheral blood, as seen in this case, thus allowing the organism to replicate in humans.  In contrast, T. cruzi trypomastigotes do not divide in blood - it is the amastigote form that divides by binary fission.

Note the trypomastigote that is preparing to divide by replicating its internal structures:

Here is a trypomastigote which has almost completely divided:

Thanks for all of the comments!


Anonymous said...

The kinetoplasts are the small circles right-most in trypomastigote?

Parasite Gal said...

Yes, the kinetoplasts are the small dot-like structures at the end furthest from the free flagellum. The flagella is actually the anterior end, so the kinetoplast is posterior. The larger purple structure in the middle of the organism is the nucleus. Thanks for all of your comments!

Anonymous said...

I thought the kinetoplast was associated with the flagellum. And in fact it is! I did not understand the morphology of the flagellum until I found this nice cartoon: