GLOSSARY

Endocytosis is the process by which a cell, by folding part of its membrane inward, surrounds extracellular material and brings it into the cell as a vesicle.
The term is formed from the Greek endo, meaning “within,” and it is the opposite of exocytosis.

Types of Endocytosis

Endocytosis has three main forms: phagocytosis, for engulfing large particles such as bacteria; pinocytosis, for drinking droplets of extracellular fluid; and receptor-mediated endocytosis, in which specific molecules first bind to membrane receptors and are then selectively taken into the cell.
A well-known example of the third type is the uptake of LDL cholesterol from the blood by cells.