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LCI產(chǎn)制滿(mǎn)足各種應(yīng)用培養(yǎng)系統(tǒng)

　　Multistep paradigm for leukocyte recruitment
　　(a)Model of a post-capillary venule illustrating the four steps of leukocyte recruitment.These are(1)initial attachment(2)low-velocity rolling(3)arrest and activation of leukocyte integrin via locally expressed chemokines and(4)transmigration.(b)Fluid shear stress.In small venules,flow has been calculated as laminar shear stress with a parabolic velocity profile(minimum velocity at the vessel wall,maximum at the center line of the vessel).Fluid shear stress also can act directly on endothelial cells and T cells.(EC,endothelial cell;BM,basement membrane.)(Reprinted with permission from Alper,J.Searching for medicine's sweet spot.Science 291,2338?2243(2001).).Copyright American Association for the Advancement of Science.Original illustration by C.Cain,redrawn by B.Crimi.)