Invagination

Invagination is the infolding of one part within another part of a structure,^[1] a folding that creates a pocket.^[2] The term, originally used in embryology, has been adopted in other disciplines as well. It has many meanings in each term or subject.

Biology

• Invagination is the morphogenetic processes by which an embryo takes form, and is the initial step of gastrulation,^[3] the massive reorganization of the embryo from a simple spherical ball of cells, the blastula, into a multi-layered organism, with differentiated germ layers: endoderm, mesoderm, and ectoderm. More localized invaginations also occur later in embryonic development,
• The inner membrane of a mitochondrion invaginates to form cristae, thus providing a much greater surface area to accommodate the protein complexes and other participants that produce adenosine triphosphate (ATP).^[4]
• Invagination occurs during endocytosis and exocytosis when a vesicle forms within the cell and the membrane closes around it.
• Invagination of a part of the intestine into another part is called intussusception.^[5]

Humanities

The term is used to explain a special kind of metanarrative. It was first used by Maurice Merleau-Ponty^[6] (French: invagination) to describe the dynamic self-differentiation of the 'flesh'. It was later used by Rosalind E. Krauss and Jacques Derrida ("The Law of Genre", Glyph 7, 1980); for Derrida, an invaginated text is a narrative that folds upon itself, "endlessly swapping outside for inside and thereby producing a structure en abyme".^[7] He applies the term to such texts as Immanuel Kant's Critique of Judgment^[7] and Maurice Blanchot's La Folie du Jour.^[8] Invagination is an aspect of différance, since according to Derrida it opens the "inside" to the "other" and denies both inside and outside a stable identity.^[2]

Geology

In geology, invagination is used to describe a deep depression of strata. Used by Donald L. Baars in "The Colorado Plateau".

References

1. "Medical Dictionary".
2. Wortham, Simon Morgan (2010). The Derrida Dictionary. Continuum International. p. 76. ISBN 9781847065261. Retrieved 12 January 2013.
3. Alberts (2002). Molecular Biology of the Cell. New York: Garland Science.
4. Cronk, Jeff. "Biochemistry Dictionary".[dead link]
5. Blanco, Felix. "Intussusception". Retrieved 1 November 2012.
6. Merleau-Ponty, Maurice (1968). The Visible and the Invisible. Boston, MA: Northwestern University Press. p. 152. ISBN 0810104571.
7. Chaplin, Susan (2004). Law, Sensibility, and the Sublime in Eighteenth-Century Women's Fiction: Speaking of Dread. Ashgate. p. 23. ISBN 9780754633068. Retrieved 12 January 2013.
8. Jones, Amelia (2003). The Feminism and Visual Culture Reader. Psychology Press. p. 200. ISBN 9780415267069. Retrieved 12 January 2013.