Morphological investigation of Toxoplasma gondii in vivo by a multiple beam interference microscope

A recently developed technique, namely multiple beam interference microscop y, has been applied to investigate the morphology of the parasite Toxoplasm a gondii for the first time. The interference pattern obtained from the mul tiple internal reflection of a T. gondii, sandwiched between a glass plate and a cover plate, was focused on the objective of a conventional microscop e. Because of the enhance contrast, several details of sub cellular structu re and separating compartments are clearly visible. Details reveal the pres ence of a nucleus, lipid body, dense granule, rhoptry and amylopectin. The wall thickness of the membrane of the lipid body and the amylopectin is of the order of 0.02 mum and can be clearly distinguished with the help of the present technique. The same parasite has also been examined with the help of atomic force microscopy, and because of its thick membrane, the inner st ructural details were not observed at all. Sub cellular details of T. gondi i observed with the present technique have been reported earlier only, by l ow amplification transmission electron microscopy and not by any optical mi croscopic technique.