Sexual stages in trypanosomes and implications.

The basis for concluding that a system of genetic exchange exists in African trypanosomes of the Trypanosoma brucei group is outlined by the accumulated data from variation in natural parasite populations and from laboratory crossing experiments. The results indicate that these parasites can complete their life cycle either with or without genetic exchange. This sexual event involves meiosis and syngamy, but the order of these processes and the sexual stages involved are not yet known.