title: In vitro excystation of Echinostoma paraensei (Digenea: Echinostomatidae) metacercariae assessed by light microscopy, morphometry and confocal laser scanning microscopy.
abstract: Trypsin and bile salts have been identified as important triggers for excystation of Echinostoma metacercariae. Although excystation in trematodes is a well-known phenomenon, some morphological developmental changes remain to be elucidated. In order to gain further insight into the in vitro development of metacercariae, we assayed different cultivating conditions: 0.5% trypsin and 0.5% bile salts; 1% trypsin and 1% bile salts; 1% trypsin and 0.5% bile salts; 0.5% bile salts; or 0.5% trypsin. By means of light microscopy and confocal microscopy, we characterized each encysted, activated, breached and excysted stage based on the morphological features. However, breached and excysted stages were not revealed in both bile salts and trypsin-free medium. Excretory concretions (25 ± 3.9) were visualized within excretory tubules, close to the ventral sucker and genital anlage. The oral sucker armed with spines and digestive system was similar to those of adult worms. The reproductive system is composed of a genital anlage and the cirrus sac primordium. In short, trypsin and bile salts associated were fundamental for the in vitro metacercariae excystation of Echinostoma paraensei. This article presents the first detailed information of all stages of metacercariae excystation obtained through light and confocal microscopy.
authors.affiliation: Romero Lascasas Porto Laboratory of Helminthology, Department of Microbiology, Immunology and Parasitology, School of Medical Science, Biomedical Center, Av. Prof. Manoel de Abreu 444/5 andar, Vila Isabel, 20511-070 Rio de Janeiro, Brazil.
authors.forename: Joyce
authors.initials: J
authors.lastname: Souza
authors.forename: Juberlan
authors.initials: J
authors.lastname: Garcia
authors.forename: Renata H
authors.initials: RH
authors.lastname: Neves
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Machado-Silva
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Maldonado
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology; D003470:Culture Media; D004449:Echinostoma / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D058488:Metacercariae / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D018613:Microscopy, Confocal; D014357:Trypsin / Q000494:pharmacology
chemical_list: D001647:Bile Acids and Salts; D003470:Culture Media; D014357:Trypsin
keywords: Confocal laser scanning microscopy; Echinostoma paraensei; Excystation; In vitro; Metacercariae; Morphology