Ultrastructure of the Midgut Epithelium in Dactylobiotus Dispar (Tardigrada: Eutardigrada) During Encystation

Abstract

Ultrastructure of the Midgut Epithelium inDactylobiotus Dispar(Tardigrada: Eutardigrada) During EncystationTardigrada are invertebrates which are able to survive unfavorable conditions of the environment by e.g. encystation. Histolysis of the animal tissues during encystation has been suggested for many species of Tardigrada, while it has not been observed inDactylobiotus dispar.The midgut epithelium plays a role in digestion, secretion, absorption and even in osmoregulation. During encystation inD. disparthe digestion is inhibited, and the midgut lumen is devoid of nourishment. Numerous lipid droplets, vesicles, and multivesicular bodies accumulate in the cytoplasm of epithelial cells. We described the ultrastructure of the midgut epithelium in encysted specimens ofD. dispar.

The fine structure of the midgut epithelium in Xerobiotus pseudohufelandi (Iharos, 1966) (Tardigrada, Eutardigrada, Macrobiotidae)

“…In Isohypsibius granulifer granulifer Thulin, 1928 (Eutardigrada) numerous structures with reserve material accumulate gradually in the cytoplasm of the midgut digestive cells as oogenesis occurs (RostRoszkowska et al, 2011a). The presence of reserve material in the cytoplasm of the digestive cells has also been described in the eutardigrade Dactylobiotus dispar (Murray, 1907) (Ząbczyk, 2000;Rost-Roszkowska and Poprawa, 2008). In case of X. pseudohufelandi differences in the amount of reserve material were not observed between midgut cells of males and females.…”

“…The amount of reserve material (e.g. lipids, proteins, saccharides) in the tardigrade midgut cells increases to enable the survival of the animal in case of, for example, starvation or any other external stress factor (Greven, 1976;Pirch and Greven, 1994;Rost-Roszkowska and Poprawa, 2008). In Isohypsibius granulifer granulifer Thulin, 1928 (Eutardigrada) numerous structures with reserve material accumulate gradually in the cytoplasm of the midgut digestive cells as oogenesis occurs (RostRoszkowska et al, 2011a).…”

Ultrastructural changes in the midgut epithelium ofHypsibius dujardini(Doyère, 1840) (Tardigrada, Eutardigrada, Hypsibiidae) in relation to oogenesis

“…To date, the structure and ultrastructure of the midgut epithelium has been studied in several tardigrade species (Marcus, ; Greven, ; Dewel, Roush & Dewel, ; Dewel et al ., ; Pirch & Greven, ; Ząbczyk, ; Avdonina et al ., ; Rost‐Roszkowska & Poprawa, ; Rost‐Roszkowska et al ., , ; Rost‐Roszkowska, Poprawa & Kaczmarek, ; Biserova & Mustafina, ); however, the relationship between changes in the midgut epithelium and changes in the gonad has only been described for the hermaphroditic Isohypsibius granulifer granulifer Thulin, 1928 (Rost‐Roszkowska et al ., ). The midgut epithelium of tardigrades is one of the tissues that, together with fat body, storage cells, trophocytes, and oocytes, are responsible for the synthesis of the yolk and chorion components, e.g.…”

Tardigrada

“…The secretion mechanism of the stylets and stylet supports and the organization of their associated musculature suggest that these structures are modifi ed limbs (Halberg et al 2009 ;Nielsen 2012 ;Ou et al 2012 ). The pharyngeal bulb is followed by a short esophagus, a simple midgut, and a short, ectodermal hindgut (Dewel and Clark 1973a , b , c ;Greven 1976 ;Dewel and Dewel 1979 ;Dewel et al 1993 ;Rost-Roszkowska and Poprawa 2008 ;Nielsen 2013 ). Tardigrades generally feed on bacteria, algae, plant matter, and other microorganisms, while a few predatory species feed on nematodes and rotifers (Marcus 1927 ;Doncaster and Hooper 1961 ;Kinchin 1994 ;Hohberg and Traunspurger 2009 ;Schill et al 2011 ).…”