New insights on the morphology of a digenean parasite (Digenea: Brachylaimidae,Brachylaima mazzantii(Travassos, 1927)) using confocal laser scanning microscopy

Abstract

Brachylaima mazzantii (Travassos, 1927) is known only from its original description. Until now, no attempt has been made to address the morphology of this species by means of modern microscopy techniques. In the present study, the information generated on the anatomy of B. mazzantii allowed the re-examination of the morphology of this species. The most significant new data is related to the terminal genitalia. The detailed analysis of the reproductive system of this species evidenced the presence of a seminal vesicle external to the cirrus pouch which contains a short unarmed cirrus, and also the presence of a well developed metraterm and gland cells in the genital atrium. The results also revealed some traits concerning other systems, previously unnoticed, including the shape and relative position of the excretory vesicle and the tegument ornamentation. The main advantage of using confocal microscopy to study the morphology of digeneans is the fact that with only one technique it is possible to examine the gross anatomy, cell morphology and surface topography. Confocal tomographies show much more detail than light microscopy images, and allow getting information on cell morphology, usually achieved only by histological techniques, along with some information on tegument ornamentation, usually obtained through scanning electron microscopy. The accumulation of information on the morphology of different digenean species through confocal microscopy will allow future comparative studies, which may ultimately contribute to the better resolution of the systematics of this group.

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

“…Previous works showed in detail the female reproductive system, and our results using LM have confirmed the morphological and morphometric patters presented in these classical descriptions (Travassos, 1944; Travassos et al ., 1969). Nevertheless, confocal images showed a single ovary filled with numerous oocytes, a conserved character among digenean trematodes (Neves et al ., 2005; Souza et al ., 2011; Hanna, 2015; Marques et al ., 2017), highlighting that reproductive efficiency is an important adaptation of the organisms to parasitic life. Laurer's canal is a structure present in digenean species.…”

“…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). Despite the excellent resolution to characterize the surface structures in detail, conventional scanning electron microscopies (SEMs) limit the observation to the external surfaces, missing information about the internal ones.…”