capillary permeability [L, capillaris, hairlike, permeare, to pass through] , a condition of the capillary wall structure that allows blood elements and waste products to pass through the capillary wall to tissue spaces. Capillaries are selectively permeable, preventing passage of some molecules and permitting others. A balance is normally present between the amount of plasma entering the tissues from the capillaries and the amount reentering the circulatory system. The lining of the capillary may be affected by inflammation or injury, resulting in increased capillary permeability. The increased permeability allows more fluid to enter the tissues, resulting in swelling and/or edema.
