Intestine samples of Bufo sp. tadpoles with parasitism confirmed for
Giardia agilis were studied by transmission electron microscopy. The
G. agilis trophozoites were long and thin. The plasma membrane was
sometimes undulated and the cytoplasm, adjacent to the dorsal and ventral
regions, showed numerous vacuoles. The two nuclei presented prominent
nucleoli. The cytoplasm was electron-dense with free ribosomes, glycogen
and rough endoplasmic reticulum-like structures. Polyhedral inclusions were
observed in the cytoplasm and outside the protozoan; some of these
inclusions exhibited membrane disruption. The flagella ultrastructure is
typical, with the caudal pair accompanied by the funis. Next to the
anterior pair, osmiophilic material was noticed. The ventro-lateral flange
was short and thick, supported by the marginal plates that penetrated into
its distal extremity; only its distal portion had adjacent osmiophilic
filament. The G. agilis trophozoites showed the general subcellular
feature of the genus. However, the ventro-lateral flange ultrastructure was
an intermediate type between G. muris and G. duodenalis. {P}
