invaginate

To enclose or become enclosed in a sheath or similar covering.

To turn or become turned inward.

To infold or become infolded so as to form a hollow space within a previously solid structure, as in the formation of a gastrula from a blastula.

To sheathe; insert or receive as into a sheath; introvert: opposed to evaginate.

To insert as in a sheath; to produce intussusception in.

Sheathed.

Having one portion of a hollow organ drawn back within another portion.

To fold up or enclose into a sheath-like or pouch-like structure, either naturally or as part of a surgical procedure.

To turn or fold inwardly.

Infolding to create a hollow space where none had existed, as with a gastrula forming from a blastula.