Additional study of the morphology of eggs and miracidia of Eurytrema coelomaticum (Trematoda)

Abstract

SummaryThe morphology of the eggs and miracidia of Eurytrema coelomaticum was analyzed. The eggshell presented different composition according to the maturation stage of the egg, as seen by distinct birefringence after polarized light microscopic analysis. Detailed morphology of the brownish eggs, measuring 44.97±3.83 (38.67 -51.40) μm in length and 30. 71±2.54 (25.79 -34.47) μm in width, and the different electrondensities of the inner, middle and outer layers of the eggs were determined using light (bright fi eld and DIC) and electronic microscopy (scanning and transmission). The morphometry of the eggs is in accordance to those measures presented in previous studies. The miracidia were observed using light microscopy, inside and outside the egg. It was possible to observe the terebratorium at the anterior end of the body, the ciliated epidermal plates, placed according the formula E=2E 1 + 2E 2 , and the interepidermal ridge, but eyespots were not observed. The excretory vesicle was laterally placed in the posterior middle of the body and the germ balls were observed. The miracidium inside the egg was observed by routine techniques, but the miracidium was not well preserved. Thus, the eggs were processed using high pressure-freeze substitution technique and reasonable preservation was achieved. The cilia covering the larval body, with a typical ciliary organization, the terebratorium with folds and the junction of the epidermal ciliated cell with the larval body were seen. For the fi rst time detailed information on the eggs and miracidia of E. coelomaticum is given, which can be the basis for new studies.

Description of embryonic development and ultrastructure in miracidia of Cardiocephaloides longicollis (Digenea, Strigeidae) in relation to active host finding strategy in a marine environment

“…High‐pressure freezing, freeze substitution or vacuum was used in other studies of trematodes (e.g., Jones et al, ; Khampoosa et al, ; Pinheiro et al, ; Świderski et al, ) to achieve a better infiltration of the egg with fixation and embedding media. In our case and in contrast to our expectations, special methods were not necessary for C. longicollis eggs as conventional TEM‐methodology was sufficient to preserve the egg structure and permit the ultrathin sectioning of the eggs.…”

Eurytrema coelomaticum: updated morphology of adult worms using advanced microscopy experiments

“…The adult worms were collected from the pancreas of naturally infected cattle that were slaughtered in an industrial slaughterhouse (Matadouro Municipal de Barra Mansa), Barra Mansa, RJ, Brazil, 22°32′39″S, 44°10′17″W) according to the sanitary surveillance rules (Pinheiro et al ., 2015). The parasites were fixed by immersion in AFA solution(the mixture by glacial acetic acid 2%, formaldehyde 3% and 70º ethanol 95%) at room temperature.…”

“…In Brazil, morphological and molecular data indicate that E. coelomaticum is the only species parasitizing livestock (Travassos, 1944; Travassos et al ., 1969; Figueira et al ., 2014). The ultrastructural organization of E. coelomaticum cercariae, mother and daughter sporocysts (Franco-Acuña et al ., 2011; Pinheiro et al ., 2011, 2012), and eggs (Pinheiro et al ., 2015) has been investigated using scanning and transmission electron microscopies. Other works have already used advanced microscopy experiments for investigating nematodes (Adnet et al ., 2013; Lopes-Torres et al ., 2015), cestodes (Almeida et al ., 2015) and some trematode species (Machado-Silva et al ., 1998; Souza et al ., 2011, 2017; Gonçalves et al ., 2016; Marques et al ., 2017).…”

Ultrastructure of digenean trematode eggs (Platyhelminthes: Neoophora): A review emphasizing new comparative data on four European Microphalloidea

“…Krejci and Fried (1994) and Fujino et al (2000) reported relatively smooth surfaces for the eggs of several echinostomatid species. Similarly, Eurytrema coelomatica eggs seem to have a nearly smooth or only slightly sculptured surface (Pinheiro et al 2015). Shell sculpturing seems to be a consistent character for any given species, and its distinctive characteristics are identifiable even after thousands of years mummified within their deceases hosts (Shin et al 2009).…”