The versatile stellate cell – More than just a space-filler

Most epithelia contain multiple cell types that interact to perform the roles required of the tissue. In insect epithelia, the apical plasma membrane V-ATPase dominates ion-transport models, and (as in vertebrates) is usually found in specialized intercalated cell types or regions. The Malpighian tubules of several insect Orders contain not just a mitochondrion-rich principal cell expressing high levels of V-ATPase, but a smaller, intercalated “type II”, “secondary” or “stellate” cell. Recent data show that this cell type plays a key role in control of chloride and water flux across the tissue, but also may play other, still unsuspected dynamic roles.

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► Malpighian tubules perform key excretory functions in most insects.
► Several insect Orders have stellate, as well as larger principal, cells.
► In Diptera, stellate cells play a key role in regulating chloride and water flux.
► Recent data imply further functional richness and dynamic roles for these cells.
► It is not known how these roles are performed in tubules that lack stellate cells.