Vitellocyte ultrastructure in the cestode Didymobothrium rudolphii (Monticelli, 1890): possible evidence for the recognition of divergent taxa within the Spathebothriidea

Abstract

In the spathebothriidean tapeworm Didymobothrium rudolphii (Monticelli, 1890) the fine structure of the vitellocytes at different stages of their development within the vitelline follicles, vitelline ducts and uterus was studied for the first time using transmission electron microscopy. The vitellocyte inclusions of D. rudolphii are shell globule clusters containing tightly packed shell globules associated with a matrix of moderate electron density, glycogen granules, large electron-lucent lipid droplets (up to 3 μm in diameter), and, occasionally, a lipid droplet may occur in the nucleus of the vitellocytes. The diameter of the clusters ranges from 0.4 to 2.5 μm, the number of shell globules in the clusters varies from 8 to 45, and the size of the globules ranges from 0.12 to 0.25 μm and they are of approximately homogeneous sizes within a cluster. Most vitellocyte lipid droplets have a heterogeneous configuration with a ‘cavity’ inside them when they are within vitelline ducts and intrauterine eggs. Vitellocytes of the eggs contain dark concentric bodies and lipid droplets. The interstitial tissue has a syncytial structure. The morphological parameters of the diameter and shape of shell globule clusters, arrangement of shell globules in clusters, number and diameter of globules within clusters, types of lipid droplets and presence of dark concentric bodies are compared with those of two other spathebothriidean genera, Cyathocephalus and Diplocotyle. The comparative data demonstrate that vitelline material morphology has unique features in three spathenothriidean genera and may be used as evidence for the recognition of separate taxa.

Ultrastructural and cytochemical studies on vitellogenesis in the trypanorhynch cestode Parachristianella trygonis Dollfus, 1946 (Eutetrarhynchidae)

“…The general pattern of vitellogenesis in P. trygonis is similar to that in other lower cestodes, namely the pseudophyllideans (OEwiderski and Mokhtar 1974, Korneva 2001, Levron et al 2007, spathebothriideans Poddubnaya et al 2005Poddubnaya et al , 2006, tetraphyllideans (Mokhtar-Maamouri and OEwiderski 1976), nippotaeniids (Korneva 2002), gyrocotylids (Xylander 1987), amphilinids (Xylander 1988), caryophyllideans (Mackiewicz 1968, OEwiderski and Mackiewicz 1976, Poddubnaya et al 2003 and to two …”

“…In P. trygonis, there are massive concentrations of lipids that, like those of G. erinaceus, and P. pastinacae, are of the saturated type. In four trypanorhynch species, the large numbers of lipid droplets were localised only in the vitellocyte cytoplasm, never inside the cell nuclei as reported in the tetraphyllidean Echeneibothrium beauchampi by Mokhtar-Maamouri and OEwiderski (1976) or the spathebothriidean Didymobothrium rudolphii by Poddubnaya et al (2006). Studies by Smirnov and Bogdan (1998) have shown that the degree of unsaturation of lipids between the pseudophyllideans Eubothrium crassum and Diphyllobothrium dendriticum was related to definitive host temperature.…”

“…Note a high accumulation of glycogen adjacent to numerous lipid droplets of moderate electron density and long parallel cisternae of GER situated just under cell plasma membranes (10) In P. trygonis vitellocytes, there was no trace of the socalled "glycan vesicles", described by Schmidt (1998) from the trematodes Fasciola hepatica and Echinostoma caproni, that were regarded as similar to the "yolk globules" of Fasciola as described by Irwin and Threadgold (1972). One should note that the "lamellar" granules of Bruòanská et al (2005) and "dark concentric bodies" of Poddubnaya et al (2006) from vitellocytes of intrauterine eggs of spathebothriidean cestodes were also considered similar to the yolk globules of Fasciola. Until the relationship of "glycan vesicles" to "lamellar" granules in cestodes is clarified, the extent of their occurrence and role in cestodes with operculate eggs must remain unknown.…”

Reinvestigation of vitellogenesis in Caryophyllaeus laticeps (Pallas, 1781) (Cestoda, Caryophyllidea, Caryophyllaeidae), monozoic tapeworm of Abramis brama (Pisces, Teleostei)

“…Ultrastructural characters of the vitellarium might be useful .... for a better understanding of the relationships between different taxa within the neoophoran Platyhelminthes (Gremini & Falleni, 1998) including Cestoda (Świderski & Mackiewicz, 1976;Świderski & Xylander, 2000;Bruňanská et al, 2005;Poddubnaya et al, 2006Poddubnaya et al, , 2012Levron et al, 2007). The structure and composition of eggshell-forming globules in vitellocytes have been considered to be especially phylogenetically informative (Gremigni & Falleni, 1991;Falleni et al, 2001).…”

“…To date, limited data are available on vitellogenesis in the Caryophyllidea, one of the basal groups of the Eucestoda. Out of about 150 species of four currently recognised families (Mackiewicz, 1994;Oros et al, 2008) seven members belonging to the two families (Caryophyllaeidae, Lytocestidae) were studied, namely Archigetes sieboldi (by Poddubnaya et al, 2003;Bruňanská et al, 2012b), Caryophyllaeus laticeps (Pallas, 1781) (by Ortner-Schönbach, 1913;Mackiewicz, 1968;Świderski et al, 2004a;Bruňan-ská et al 2010), Caryophyllaeides fennica (by Mackiewicz, 1968), Glaridacris catostomi (by Świderski & Mackiewicz, 1976), Wenyonia virilis (by Świderski et al, 2009), Atractolytocestus huronensis (by Bruňanská et al, 2009), Khawia armeniaca (by Świderski et al, 2004b) and Monobothrioides chalmersius (by Arafa 2012). As far as C. laticeps is concerned, the first histological and histochemical investigation on vitellogenesis was based on light microscopy (Mackiewicz, 1968), and supplemented by ultrastructural data in two brief abstracts (Świderski et al, 2004a(Świderski et al, , Bruňanská et al, 2010.…”