Infectivity of monomorphic and pleomorphic trypanosoma brucei stocks cultivated at 28 C with various tsetse fly tissues.

Noninfective procyclic forms of Trypanosoma brucei stocks derived from the pleomorphic EVE 10 were cultivated at 28 C in Cunningham's liquid medium in the presence of head-salivary gland, alimentary tract, and abdominal body wall explants of Glossina morsitans morsitans. After 8 to 10 days of cultivation some of the procyclic forms transformed into metacyclic stages infective for mice. Infectivity persisted for varying periods up to 66 days, when the experiments were terminated. Only 10 explants of alimentary tract or abdominal body wall tissues were required in the flasks to render the culture infective for most of the mice inoculated. Similar trypanosome suspensions grown with 10 head-salivary gland explants produced an infection on only one occasion. Cultures of procyclic organisms derived from the monomorphic stock 427 grown inthe presence of all three types of tsetse fly explants produced only sporadic infections in mice. Metacyclic forms failed to develop in trypanosome populations of stock EVE 10 cultivated at 28 C in the liquid medium alone or supplemented with mouse embryo tissues.