Giardia agilis: ultrastructure of the trophozoites in the frog intestine

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 extermity; 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.

Ultrastructure of Giardia duodenalis trophozoites group from hamster: some relevant aspects

Throphozoites of Giardia duodenalis group obtained from fragments or scratched of hamster's mucosa were examined by transission electron microscopy. The fine structure of the trophozoites are presented and comapred with those described for other animals. Some of the trophozoites present the cytoplasm full of glycogen, rough endoplasmic reticulum-like structures and homogeneous inclusions not enclosed by membranes, recognized as lipid drops, which had not been observed in Giardia from other animals. The adhesive disk is composed of a layer of microtubules, from which fibrous ribbons extend into the cytoplasm; these ribbons are linked by layer of crossbridge filaments that shows an intermediary dense band, described for the first time in this paper. The authors regard this band as the result of the cross-bridge filaments slinding in the medium region between adjacent fibrous ribbons, and suggest a contractile activity for them. The role of the adhesive disk on the trophozoite mechanism of attachment to host mucosa is also discussed

Giardia lamblia attachment to biological and inert substrates

El análisis de las bases estructurales de la adhesión de trofozoítos de Giardialamblia cepa 1/Potland a monocapas confluentes de células MDCK (Madin Darby Canine Kidney) y a capas de colágena del tipo I proporciona evidencias a nivel de microcospía fotónica y electrónica de que el disco ventral así como el borde ventrolateral son las estructuras de adhesión al sustrato. Además se observó que la adhesión del trofozoítos es más efectiva sobre la colágena que sobre al superficie apical del epitelio. Se describe por primera vez la presencia de una estructura circular en forma de bolsa evaginada del área desnuda que parece ser el sitio del disco ventral de contacto íntimo del trofozoíto con el sustrato. Dicha estructura ha sido también observada cuando se da la adhesión del trofozoíto a la superficie de vidrio del cubreobjeto o aún cuando se establece el contacto estrecho entre trofozoítos

Giardia muris and Giardia duodenalis groups: ultrastructural differences between the trophozoites

Neste trabalho foi analisada, através de Microscopia Eletrônica de Transmissäo, a morfologia de trofozoitos de Giardia muris obtidos de hamsters, ratos peridomiciliares e camundongos, bem como de trofozoitos de Giardia duodenais obtidos de hamsters e ratos peridomiciliares . Basicamente a ultraestrutura dos trofozoitos estudados foi semelhante. Foram observadas, no entanto, diferenças na morfologia de franja ventro-lateral dos trofozoitos de Giardia muris quando comparados com os de Giardia duodenalis, diferenças estas relacionadas ao tamanho, arranjo das lâminas marginais e presença de lamela osmiofílica