Transmission electron microscopy of sensory receptors ofEchinostoma revolutum (Froelich 1802) cercaria (Digenea: Echinostomatidae)

Zdárská, Z

doi:10.1007/bf00936459

Cited by 18 publications

(5 citation statements)

References 23 publications

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“…They are grouped in the following major categories: 1.0 -Nonciliated receptors, with no cilia emerging through the tegument: 1. with a moderately low to very high tegumentary collar, short or long unsheathed cilia, a central pair of microtubules, a basal body, a sensory bulb attached to the tegument by septate extracellular junctional complexes and two pairs of thickened nerve collars. Some of these types are similar to types previously described (Køie 1981, Žďárská 1992, Moravec 2002.…”

Section: Functional Componentssupporting

confidence: 80%

Functional and phylogenetic components in cercarial nervous systems

Bogéa¹

2004

FOLIA PARASIT

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Abstract. Studies involving comparisons of taxa that vary in their degree of relatedness may allow the distinction of functional and phylogenetic components in cercarial sensory systems. In this study, cercariae of allocreadiids Bunodera Railliet, 1896 and Crepidostomum Braun, 1900, lecithodendriid Allassogonoporus Olivier, 1938 and opecoelid Allopodocotyle Pritchard, 1966 were compared as regards ultrastructure and chaetotaxy of sensory receptors as well as neuromorphology. Cercariae were treated with acetylthiocholine iodide and silver nitrate and some were processed for scanning and transmission electron microscopy. The types of cercarial sensory receptors differed in the presence of a tegumentary sheath, a dome-like base and a tegumentary collar, number of cilia (0, 1, 2 or more), cilium length (short, moderately long or long) and tegumentary collar length (low to moderately low, high or very high). Chaetotaxic patterns were consistent at the family level in all taxa studied. Irregular cholinergic nerve networks were identified. The present study indicates that the major categories of cercarial sensory receptors are nonciliated (including sheathed and subtegumentary types) and ciliated (including uncollared and collared types) receptors. It also allows the distinction of functional and phylogenetic components in the sensory systems of the cercariae studied. Functional components were reflected in the numbers of sensory receptors associated with each nerve region and in the ultrastructure and site-specificity of receptor types. Phylogenetic components included taxon-specific chaetotaxic patterns and receptor types.In the past, the investigation of cercarial sensory systems had emphasised the morphology and distribution of receptor types. Ultrastructural studies have revealed the existence of several types of receptors across the larval tegument of Digenea (Halton et al. 1997). These types suggest that different forms are associated with distinct functions. Site-specificity of receptor types also supports this idea in several species (Bogéa and Caira 2001a, b, c). Functional components are more strongly implicated when similar site-specific patterns are found among distant related taxa, particularly in those that share life-cycle strategies.Sensory receptor types found to be restricted to groups of related species, on the other hand, would suggest that there might be at least some phylogenetic components to these features. Besides, it is clear that the distribution of receptors on the cercarial tegument is phylogenetically based, with chaetotaxic patterns recognised at the family, genus and species levels (Richard 1971, Bayssade-Dufour 1979, Bayssade-Dufour et al. 1993. What remains unclear, however, is whether receptor types and/or distribution patterns of receptor types may be taxon-specific.Studies involving comparisons among taxa that vary in their degree of relatedness, therefore, emerge as a strategy that may allow distinction between functional and phylogenetic components in cercarial sensory systems....

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Section: Functional Componentssupporting

confidence: 80%

Functional and phylogenetic components in cercarial nervous systems

Bogéa¹

2004

FOLIA PARASIT

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“…The numerous sensory endings in branch tips are likely to be involved in the determination of optimal growth directions. The non-ciliated sensory endings are similar to the receptors described in cercariae of Echinostoma revolutum (type-2 non-ciliated receptors) (Žd'árská, 1992) and juvenile flukes of Fasciola hepatica (see Bennett, 1975) in having two electron-dense rings, a basal body and a well-developed cross-striated rootlet. It is commonly thought (Rohde & Watson, 1990; Czubaj & Niewiadomska, 1996; Žd'árská & Nebesářová, 2003) that non-ciliated sensory endings, which have no direct contact with the environment, are receptive to mechanical stimuli.…”

Section: Discussionsupporting

confidence: 60%

“…It is commonly thought (Rohde & Watson, 1990; Czubaj & Niewiadomska, 1996; Žd'árská & Nebesářová, 2003) that non-ciliated sensory endings, which have no direct contact with the environment, are receptive to mechanical stimuli. Sensory endings with one short cilium and an absent or weakly developed rootlet, similar to those observed in the P. borealis sporocysts, have been recorded in various life cycle stages of many digenean species, such as cercariae of E. revolutum (Žd'árská, 1992), daughter sporocysts and cercariae of D. pseudospathaceum (Czubaj & Niewiadomska, 1991, 1996), adults of Crepidostomum metoecus (Žd'árská & Nebesářová, 2003, 2004). Such sensory endings are usually believed to be mechano- or chemoreceptors.…”

Section: Discussionsupporting

confidence: 54%

Morpho-functional specialization of the branching sporocyst of Prosorhynchoides borealis Bartoli, Gibson & Bray, 2006 (Digenea, Bucephalidae)

Podvyaznaya

Галактионов

2011

J. Helminthol.

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Sporocysts of Prosorhynchoides borealis were obtained from the marine bivalves Abra prismatica and studied using transmission electron microscopy. The sporocyst body consists of a mass of branching and intertwining hollow tubules that ramify through the host's digestive gland and gonads. This study investigated the ultrastructure of the sporocyst branches which comprise alternate distended areas (brood chambers) with a relatively thin body wall, narrower portions with a thicker body wall (constricted areas) and terminal regions. Pronounced differences between these areas were revealed in the structure of their tegument and body cavity lining, as well as in the cellular composition of the subtegumental layers. Body wall composition in distended areas was consistent with the specialization for cercarial nurture in the brood chambers. The structure of the constrictions suggested a dual role of nutrient absorption and physical separation of adjacent brood chambers. Two types of terminal region were identified, one specialized for the investigation and penetration of host tissues and the other, in which the germinal cells are formed, for cercarial production. The overall structure of the sporocyst branches helps explain why this linear modular system, i.e. brood chambers and constrictions continuously growing into the host tissue, enables the sporocyst's long-term existence and can continuously produce cercariae in numbers comparable with those produced by rediae and/or daughter sporocyst infrapopulations in other digeneans. The origin of the nuclei in the outer tegumental layer of some branching bucephalid sporocysts is also discussed.

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“…Wykazały one duŜą róŜnorodność ultrastrukturalną, która wiąŜe się z róŜnorodnością ich funkcji. RównieŜ u przedstawicieli Echinostomatidae obserwowano zróŜnicowanie zakończeń czuciowych (ŽĎÁRSKÁ 1992).…”

Section: Cerkarieunclassified

Przywry (Trematoda). Część ogólna; Część systematyczna – Aspidogastrea, Digenea: Strigeida

Niewiadomska¹

2010

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Transmission electron microscopy of sensory receptors ofEchinostoma revolutum (Froelich 1802) cercaria (Digenea: Echinostomatidae)

Cited by 18 publications

References 23 publications

Functional and phylogenetic components in cercarial nervous systems

Functional and phylogenetic components in cercarial nervous systems

Morpho-functional specialization of the branching sporocyst of Prosorhynchoides borealis Bartoli, Gibson & Bray, 2006 (Digenea, Bucephalidae)

Przywry (Trematoda). Część ogólna; Część systematyczna – Aspidogastrea, Digenea: Strigeida

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