- Internalization of substances from the extracellular environment through the formation of vesicles formed from the plasma membrane. There are two forms: (a) fluid phase (pinocytosis), and (b) receptor mediated. SEE ALSO: phagocytosis. Cf.:exocytosis (2). [endo- + G. kytos, cell, + -osis, condition]
* * *en·do·cy·to·sis -sī-'tō-səs n, pl -to·ses -.sēz incorporation of substances into a cell by phagocytosis or pinocytosisen·do·cy·tose -'sī-.tōs, -.tōz vt, -tosed; -tos·ingen·do·cy·tot·ic -sī-'tät-ik adj
* * *en·do·cy·to·sis (en″do-si-toґsis) [endo- + cyt- + -osis] the uptake by a cell of material from the environment by invagination of its plasma membrane; it includes both phagocytosis and pinocytosis.
Endocytosis. (A), Membrane receptors bind to specific molecules in the extracellular fluid; (B), a portion of the plasma membrane is pulled inward by the cytoskeleton, forming a small pocket around the material to be moved into the cell; (C), the edges of the pocket fuse to form a vesicle; (D), the vesicle is pulled inward, away from the plasma membrane, by the cytoskeleton.
Medical dictionary. 2011.