Abstract
The classical Golgi apparatus has not been observed in the several strains of Tetrahymena pyriformis examined in this laboratory at the ultrastructural level when the ciliates are grown vegetatively. However, sexually active strains, when starved for the purpose of inducing conjugation, contain stacked saccules in the oral region. When such opposite mating types are mixed for mating, the stacked saccules become swollen at their ends and vesicles appear to pinch off from them. These bodies possess the configuration of the classical Golgi apparatus of other eucells. Vesicles seem to be formed from the saccules just prior to, and toward the end of conjugation, suggesting a relationship with the mating process.