Ultrastructure of the digestive system of Ramazzottius tribulosus and Macrobiotus richtersi (Eutardigrada) in relationship with diet

Abstract

The ultrastructure of the digestive system of tardigrades was already described in some species, but it has never been studied in relationship to diet.

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

“…Dactylobiotus dispar Murray, 1907 (Ząbczyk, ; Rost‐Roszkowska & Poprawa, ), Echiniscus testudo (Doyère, 1840) (Pirch & Greven, ), Echiniscus virdissimus Péterfi, 1956 (Dewel et al ., ), Halobiotus stenostomus (Richters, 1908) (Biserova & Mustafina, ), Isohypsibius augusti Murray, 1907 (Greven, ), Isohypsibius granulifer granulifer (Rost‐Roszkowska et al ., , ), Milnesium tardigradum Doyère, 1840 (Dewel et al ., ; Biserova & Mustafina, ), Paramacrobiotus richtersi Murray, 1911 (Avdonina et al ., ), Ramazzottius tribulosus Bertolani & Rebecchi, 1988 (Avdonina et al ., 2007), Richtersius coronifer (Richters, 1903) (Biserova & Mustafina, ), and Xerobiotus pseudohufelandi Iharos, 1966 (Rost‐Roszkowska et al ., ). It is mainly formed by the principal cells (the digestive cells), but also by ‘crescent‐like cells’, detected in several species (Marcus, ; Bertolani, ; Dewel & Clark, ; Greven, ; Pirch & Greven, ; Ząbczyk, ; Avdonina et al ., ; Rost‐Roszkowska et al ., , ). These ‘crescent‐like cells’ form the anterior epithelial ring (Rost‐Roszkowska et al ., ), and correspond to the ‘light cells’ described by Biserova & Mustafina () in H. stenostomus .…”

“…Among tardigrades (water bears), herbivorous species feed on bacteria and algal cells or suck fluids from plant cells, such as mosses, whereas predatory tardigrades feed on protozoa, rotifers, nematodes or even other tardigrades (Avdonina et al ., ; Nelson, Guidetti & Rebecchi, ). Most of the body of a tardigrade is filled by a gut and a gonad (especially during the advanced stages of 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.…”

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

“…The midgut epithelium of analyzed species of Tardigrada is formed by epithelial cells placed on the non-cellular basal lamina (KRISTENSEN, 1976;PIRCH and GREVEN, 1994;AVDONINA et al, 2007). No regenerative cells were described (GREVEN, 1976), but some studies revealed that the crescent-like cells of the anterior midgut were able to proliferate (BERTOLANI, 1970).…”

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

“…Up to now two kinds of cells have been described in the midgut epithelium of tardigrades: digestive cells that form the epithelium and crescent-like cells situated between the foregut and the midgut (Bertolani, 1970;Dewel and Clark, 1973;Greven, 1976;Kristensen, 1976;Pirch and Greven, 1994;Ząbczyk, 2000;Avdonina et al, 2007;RostRoszkowska and Poprawa, 2008;Rost-Roszkowska et al, 2011a). Fig.…”