Schistosoma mansoni: Development of the vitelline cell, its role in drug sequestration, and changes induced by Astiban

Ultrastructural and cytochemical studies of GER-bodies in the intrauterine eggs of Wenyonia virilis Woodland, 1923 (Cestoda, Caryophyllidea)

“…Poddubnaya et al (2006) suggested, however, that they may represent shell-globules at some level of their transformation during egg formation of Didymobothrium rudolphi. Such atypical structures were also described by Erasmus (1973Erasmus ( , 1975 in Schistosoma mansoni and were interpreted as a concentration of ribosomes or cytosegresomes. Most recent study on vitellocytes of Fasciola gigantica (Meepool et al 2006) follow the terminology proposed by Schmidt (1998) who described them as "membrane bounded glycan vesicles".…”

“…For this reason he designated such structures as "glycan vesicles". Comparing his results with those of Erasmus (1973Erasmus ( , 1975, Schmidt (1998) concluded that glycans in the vesicles are a type of glycogen and that "glycan vesicles" may be involved in the synthesis of enzymes engaged in the production of glycans and provide core proteins. Erasmus (1973) had suggested that these lamellar structures may represent ribosomal whorls, however, he did not initially suggest their function and only later classified them as cytosegresomes that are involved in focal degradation within the cell (Erasmus 1975).…”

“…In addition to above mentioned cytoplasmic inclusions, vitellocytes of some parasitic platyhelminths contain an additional type of structures, frequently lamellar, elongated or spherical, in most cases of unknown function. Such structures have been noticed in vitellocytes of different trematode and cestode species (Björkman and Thorsell 1963;Irwin and Threadgold 1970;Erasmus 1973Erasmus , 1975Halton et al 1974;Threadgold 1982;Stitt and Fairweather 1996;Schmidt 1998;Bruňanská et al 2005Bruňanská et al , 2009Meepool et al 2006;Poddubnaya et al 2006). Some authors claimed, however, that their occurrence in the trematode eggs may be related to the third important function that vitellocytes may play, namely, hatching of the larvae (Schmidt 1998, Meepool et al 2006).…”

“…Nevertheless, the presence of GER in lamellar structures observed in flatworm vitellocytes was also suggested by Irwin and Threadgold (1970), Halton et al (1974), Threadgold (1982), Schmidt (1998) and Bruňan-ská et al (2005Bruňan-ská et al ( , 2009, however, components of GER are not clearly visible and distinguishable in their micrographs. A majority of illustrations included in other papers (Björkman and Thorsell 1963;Irwin and Threadgold 1970;Erasmus 1973Erasmus , 1975Halton et al 1974;Threadgold 1982;Stitt and Fairweather 1996;Schmidt 1998;Bruňanská et al 2005Bruňanská et al , 2009Meepool et al 2006;Poddubnaya et al 2006) show only micrographs of low magnifications (×1,500-50,000) where most of details remain below a limit of resolution of light or electron microscopy. Because these inclusions have been observed at different magnifications, and therefore incomparable, it is possible that the structure and chemical composition of these It should be noted, that most of the above mentioned studies focused on trematodes.…”

“…For these structures we suggest a new term "GER-body", and compare them with other lamellar structures described in vitellocytes of trematodes and cestodes (Björk-man and Thorsell 1963;Irwin and Threadgold 1970;Erasmus 1973Erasmus , 1975Halton et al 1974;Threadgold 1982;Stitt and Fairweather 1996;Schmidt 1998;Bruňanská et al 2005Bruňanská et al , 2009Meepool et al 2006;Poddubnaya et al 2006).…”