Functional microscopic anatomy of the digestive system of Tetranychus urticae (Acari, Tetranychidae)
1981 - Volume: 22 Issue: 3 pages: 257-270
KeywordsPharyngeal partial vacuum synthesis resorption storage phagogytes excretory cells distribution
The digestive system of Tetranychus urticae is described using light and electron microscopy. It is divided into pharynx, esophagus, midgut and hindgut with anus. The midgut consists of the ventriculus, three cranial and two caudal caeca. The pharynx which is surrounded by specialised structures for food ingestion, encloses the pharyngeal sucker and opens at the top of the gnathosoma. These structures serve to form a partial vacuum, by means of which plant cell components flow into the ventriculus without permanent sucking process. Passing through the esophagus the food reaches the ventriculus and on to the caeca, where intracellular digestion starts. The midgut epithelial cells show different functions. The ventricular and cranial caecal cells are in stage of synthesis. In the caudal caeca some cells enter the stage of resorption and storage, leave the epithelium and become free cells of the midgut lumen (= phagocytes) . After passing through the midgut in direction of the hindgut sphincter they change into excretory cells. The phagocytes take over specialised functions in digestion, whereas at the same time they serve as a system of distribution for storage and nutritive products and replace the missing hemolymph system.
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