Pinocytosis

Pinocytosis (from the Greek pinein "drink" and kytos "cell") is one of the subtypes endocytosis. It receives during pinocytosis extracellular fluid (extracellular fluids = ECF).

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By engulfing invagination the cytoplasmic membrane, the cell envelops a small amount of extracellular fluid, which it traps in tiny vesicles. In the cell, these 'pinocytic vesicles merge with lysosomes and are hydrolyzed or simply used for transcytosis. The pinocytosis process requires energy in the form of ATP.

Pinocytic vesicles are formed by elements of the cytoskeleton - microtubules and especially actin microfilaments. Vesicles are up to 80 nm in diameter, compared to phagocytic vesicles which are smaller (5–20 nm).

Pinocytosis is a non-specific process, that is, the pinocytizing cell takes in the extracellular fluid as well as the substances dissolved in it as opposed to receptor-mediated endocytosis.

Articles

 * Endocytosis
 * Transmembrane transport