Answer
diapedesis or emigration
Work Step by Step
The movement of leukocytes through a capillary or venule wall is called diapedesis or emigration.
Diapedesis occurs across the walls of the postcapillary venules while emigration occurs when cells and chemicals leave the bloodstream. Both terms are correct because the leukocytes are leaving the bloodstream and crossing the walls of the postcapillary venules.
