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

Tardigrada 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 in Dactylobiotus dispar. The midgut epithelium plays a role in digestion, secretion, absorption and even in osmoregulation. During encystation in D. dispar the 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 of D. dispar.