title: The first data on the vitellogenesis of paruterinid tapeworms: an ultrastructural study of Dictyterina cholodkowskii (Cestoda: Cyclophyllidea).
abstract: The present study provides the first ultrastructural data of the vitellogenesis in a cestode species of the cyclophyllidean family Paruterinidae, aiming to expand the limited data on the vitellogenesis in cyclophyllidean cestodes and to explore the potential of ultrastructural characters associated with vitellogenesis for phylogenetic and taxonomic studies of this order. The process of vitellocyte formation in Dictyterina cholodkowskii follows the general pattern observed in other tapeworms but exhibits several specific differences in the ultrastructure of vitelline cells. The vitellarium contains vitellocytes at various stages of maturation. The periphery of the vitellarium and the space between maturing vitellocytes are occupied by interstitial cells. Differentiation into mature vitellocytes is characterized by high secretory activity, which involves the development of granular endoplasmic reticulum, Golgi complexes, mitochondria and vitelline globules of various sizes. During vitellogenesis, the progressive fusion of these globules results in the formation of two large membrane-limited vitelline vesicles that eventually fuse into a single large vesicle. Mature vitellocytes are composed of a single vitelline vesicle, a high content of cytoplasmic organelles and have no nucleus. No traces of lipid droplets and glycogen granules are detected in the cytoplasm of mature vitellocytes, which might be related to biological peculiarities of this family, i.e. the release of eggs into environment within the tissues of the paruterine organ, which may serve as a source of nutrients for embryos.
authors: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113, Sofia, Bulgaria. anetayoneva@gmail.com.|Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic. anetayoneva@gmail.com.
authors: Aneta
authors: A
authors: Yoneva
authors: Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic.
authors: Roman
authors: R
authors: Kuchta
authors: Natural History Museum of Geneva, CP 6434, 1211, Geneva 6, Switzerland.|Department of Genetics and Evolution, University of Geneva, 1205, Geneva, Switzerland.
authors: Jean
authors: J
authors: Mariaux
authors: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113, Sofia, Bulgaria.
authors: Boyko B
authors: BB
authors: Georgiev
mesh_terms: D000818:Animals; D002589:Cestoda / Q000502:physiology / Q000648:ultrastructure*; D003593:Cytoplasm / Q000648:ultrastructure; D005260:Female; D006080:Ovarian Follicle / Q000502:physiology / Q000648:ultrastructure; D010802:Phylogeny; D014817:Vitelline Membrane / Q000502:physiology; D014818:Vitellogenesis / Q000502:physiology*
keywords: Cestode; Cyclophyllidean; Dictyterina cholodkowskii; Ultrastructure; Vitelline vesicles; Vitellocytes