1963 C. De Duve in De Rueck & Cameron 412 The new term..simply indicates that materials are coming into the cell (endocytosis) rather than going out (exocytosis).
1969 N. S. Cohn (ed. 2) v. 124 Foreign protein or other material could undergo digestion within the cell as a result of such endocytosis (pinocytosis and phagocytosis).