AskDefine | Define invagination

Dictionary Definition

invagination

Noun

1 the condition of being folded inward or sheathed [syn: introversion]
2 the folding in of an outer layer so as to form a pocket in the surface; "the invagination of the blastula" [syn: introversion, intussusception, infolding]

User Contributed Dictionary

English

Pronunciation

Noun

  1. The process where an anatomical part invaginates upon itself or into another structure.
  2. One of the methods by which the various germinal layers of the ovum are differentiated.

Extensive Definition

Invagination means to fold inward or to sheath. In biology, this can refer to a number of processes.
  • Invagination is the morphogenetic processes by which an embryo takes form, and is the initial step of gastrulation, 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, to form coelom, etc.
  • 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 ATP.
  • Invagination occurs during endocytosis and exocytosis when a vesicle forms within the cell and the membrane closes around it.
In the humanities:
  • Used to explain a special kind of meta narrative. Used by Rosalyn Krauss and Jacques Derrida (The Law of Genre,” Glyph 7 (1980).
invagination in German: Invagination
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