The body of the dragonfly molts and extends its wings by pumping body fluid.
“In addition, there are a series of special mechanisms that help the dragonfly to shed its skin. The body of the dragonfly shrinks and becomes wrinkled in the old body. In order to ‘open’ this body, a special pump system and a special body fluid are created to be used in this process. These wrinkled body parts of the insect are inflated by pumping body fluid after getting out through the slot. In the meantime, chemical solvents start to break the ties of the new legs with the old ones without damage.”
“The wings are fully developed already but are in a folded position. The body fluid is pumped by firm contractions of the body into the wing tissues.” (Yahya 2002: 25-26)