Definition of "invaginate" []

• To enclose or become enclosed in or as if in a sheath. (verb-transitive)
• To turn or become turned inward. (verb-transitive)
• 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. (verb-transitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "When they wheel and dance like miniature starlings, the consequence is that three-dimensional shapes are formed, as tissues invaginate in response to the movements of cells;* or swell or shrink due to local patterns of growth and cell death."
• "Its area therefore increases and, having nowhere else to go, it has little choice but to buckle or invaginate."
• "The sheets of tissue that fold, invaginate and turn inside out in a developing embryo do indeed grow, and it is that very growth that provides part of the motive force which, in origami, is supplied by the human hand."