Videomicroscopic recording of Pneumocystis carinii motion.

Videomicroscopy in combination with differential-contrast optics was used to study fresh preparations of Pneumocystis carinii from immunosuppressed rats. Certain spherical intracystic bodies appeared to move freely within the cyst wall. Flexing type movement was observed in intracystic ellipsoidal forms attached at a common point in the inner margin of the cyst wall. Greater movement was seen in non-attached thinner elongated forms. Possible extracellular trophic forms and movement were also identified. The movement of the morphological forms of P. carinii has been recorded in real time onto videotape. These initial observations suggest P. carinii is capable of movement and additional studies are under way to substantiate this possibility.