- A cellular process that permits the active transport of fluid from outside the cell through the membrane surrounding the cell into the inside of the cell. In pinocytosis, tiny incuppings called caveolae (little caves) in the surface of the cell close and then pinch off to form pinosomes, little fluid-filled bubbles, that are free within the cytoplasm of the cell.
* * *The cellular process of actively engulfing liquid, a phenomenon in which minute incuppings or invaginations are formed in the surface of the cell membrane and close to form fluid-filled vesicles; it resembles phagocytosis. [pinocyte + G. -osis, condition]
* * *pi·no·cy·to·sis .pin-ə-sə-'tō-səs, .pīn-, -.sī- n, pl -to·ses -.sēz the uptake of fluid and dissolved substances by a cell by invagination and pinching off of the cell membrane
* * *n.the intake of small droplets of fluid by a cell by cytoplasmic engulfment. It occurs in many white blood cells and in certain kidney and liver cells. Compare phagocytosis.
* * *pino·cy·to·sis (pin″o-) (pi″no-si-toґsis) [Gr. pinein to drink + cyto- + -osis] the cellular uptake of extracellular fluid and its contents by enclosing them in vesicles derived from the plasma membrane; it serves as a method of transport for macromolecules. Cf. macropinocytosis. pinocytotic adj
Mechanism of pinocytosis of extracellular proteins.
Medical dictionary. 2011.