In Vitro Reversible Transformation of Leishmania braziliensis panamensis Between Promastigote and Ellipsoidal Forms

Raising the temperature of a log‐phase culture of Leishmania braziliensis panamensis promastigotes from 26°C to 34°C resulted in formation of a culture containing 85% ellipsoidally shaped forms after 1.5 h. The temperature‐induced ellipsoidal forms decreased in size but persisted in high proportion (85–95%) for at least 12 h at 34°C. Recovery from the ellipsoidal forms to a culture containing 85–95% promastigotes was observed after returning the temperature to 26°C. The time required for recovery increased markedly with the duration of the preceding heat treatment, up to about 70 h for a 12‐h heat treatment.