CBSE Class 9 Answered

The WBCs can change their shape easily and this allows them to squeeze through walls of the blood vessels into the inter-cellular spaces. Due to this, they can also stick to the walls of the blood vessels and engulf any foreign particles that try to enter the bloodstream. Some of the WBCs can carry out the function of phagocytosis. For this, they take on a flattened and ruffled appearance characterized by pseudopods. This leukocyte will move with repetitive wavelike motions until they reach the site of infection. Movement to the site of infection is also possible due to this shape change of WBC.