Ultrastructural study of vitellogenesis and oogenesis of Metadena depressa (Stossich, 1883) Linton, 1910 (Digenea, Cryptogonimidae), intestinal parasite of Dentex dentex (Pisces, Teleostei)

Abstract

E ´tude ultrastructurale de la vitellogene`se et de l'ovogene`se de Metadena depressa (Stossich, 1883) Linton, 1910 (Digenea, Cryptogonimidae), parasite intestinal de Dentex dentex (Pisces, Teleostei

Ultrastructural study of vitellogenesis and oogenesis ofCrepidostomum metoecus(Digenea, Allocreadiidae), intestinal parasite ofSalmo trutta(Pisces, Teleostei)

“…This material, named either “chromatoid body”, “nuclear extrusion”, or “nucleolus-like cytoplasmic body” [4, 18, 27, 35], probably contains RNA [4, 25]. This structure is often surrounded by mitochondria and granular endoplasmic reticulum [14], as in the present study. Movements of mitochondria during oogenesis were described by Yosufzai (1952), who studied this in Fasciola hepatica , where mitochondria are at one pole of oogonia, then form a ring around the nucleus in growing oocytes, and are finally evenly distributed in the cytoplasm of mature oocytes [52].…”

“…Some vitelline follicles of Digenea possess interstitial cells (or nurse cells) with cytoplasmic extensions between vitellocytes that are believed to be involved in the selection and transport of materials from the parenchyma to the developing vitelline cells [1, 13, 14, 28]. In Crepidostomum metoecus , as in Plagiorchis elegans , or Maritrema feliui , nurse cells were not found [15, 46].…”

“…The initial phase of oocyte maturation takes place during the prophase of the first meiotic division in the ovary. As for Metadena depressa [14], no nucleus has been observed in the thin interstitial cytoplasmic layer between growing oocytes and the basal lamina, unlike in other Platyhelminthes where syncytial structures may occur in the ovary [34]. Oogonia are present along the wall of the ovary as for Cryptocotyle lingua [5], but do not contain a nucleolus-like Zygocotyle lunata [49].…”

Functional ultrastructure and cytochemistry of vitellogenesis and mature vitellocytes of the digenean Cainocreadium labracis (Dujardin, 1845), parasite of Dicentrarchus labrax (L., 1758)

“…)cGER (=GERb? )DISBAllocreadiidae Crepidostomum metoecus ++Sβ++Greani et al (2016)Azygiidae Azygia lucii ++S++Poddubnaya et al (2012)Cryptogonimidae Aphallus tubarium ++Sβ++Greani et al (2012a) Metadema depressa ++Sβ++Greani et al (2012b)Diplostomidae Pharyngostomoides procyonis deg.+Sβ++Grant et al (1977)Fasciolidae Fasciola hepatica ++α, β++Irwin and Threadgold (1970)Gorgoderidae Gorgoderina vitelliloba ++S++Irwin and Maguire (1979) Phyllodistomum angulatum ++S+Poddubnaya et al (2012)Microphallidae Maritrema feliui –+SβŚwiderski et al (2011) M. linguilla deg./−+S–+–Hendow and James (1989…”

Ultrastructural and cytochemical aspects of the germarium and the vitellarium in Syndesmis patagonica (Platyhelminthes, Rhabdocoela, Umagillidae)

“…A different situation has been observed in the oocytes of the rhabdocoel Temnocephalida belonging to Temocephalidae and Scutariellidae where peripheral egg granules, devoid of polyphenols and containing glycoproteins, have been interpreted as cortical granules (Falleni et al, ). Cortical granules have also been found in the oocytes of some Proseriata (Gremigni and Nigro, ; Gremigni et al, ; Sopott‐Ehlers, ), Tricladida belonging to Planariidae and Dendrocoelidae (Gremigni, ; Gremigni and Domenici, ; Harrath et al, ) and in the parasitic Neodermata (Justine and Mattei, ; Cifrian et al, ; Justine et al, ; Yang et al, ; Poddubnaya et al, ; Greani et al, ). These peripheral granules, which have a glycoprotein content and are devoid of polyphenols, are thought to be a tool to prevent polyspermy even though their role in the process of fertilization and disappearance in fertilized eggs has rarely been ascertained (Gremigni and Domenici, ; Sopott‐Ehlers, ).…”