​What is Pathology - What are the major events that cause leukocytes to transmigrate across the vessel wall?

What is Pathology - ​What are the major events that cause leukocytes to transmigrate across the vessel wall?
 Margination: As blood flow slows, neutrophils are able to move from the centre of the bloodstream to the periphery, where they can make contact with endothelial cells. & Rolling: Leukocytes, which typically circulate in the bloodstream, continue to roll over endothelial cells. Leukocytes and endothelial cells become stimulated and form loose connections with one another throughout this process. Selectins, which are surface adhesion molecules, facilitate these interactions. 
Adhesion: As leukocytes and endothelial cells become more activated, integrins, polypeptide adhesion molecules, are produced. Integrins on neutrophils' surfaces bind to complementary integrins or endothelial cells, forming a strong bond between them. 
Transmigration: Neutrophils that have been linked to endothelial cells by integrins take on an amoeboid shape and begin crawling across the inside surface of venules until they reach the intercellular gaps. Finally, leukocytes squeeze through the intercellular gaps and emerge from the arteries' intercellular spaces.