Final answer:
Diapedesis is due to the amoeboid ability of leukocytes to move through tissues in response to chemical signals from infected or injured cells. Leukocytes perform various immune functions, including phagocytosis and releasing chemicals to destroy pathogens.
Step-by-step explanation:
Diapedesis to a site of infection is due to the amoeboid ability of leukocytes. This process, also called emigration, is where leukocytes squeeze through adjacent cells in the walls of blood vessels to enter the tissues. Leukocytes such as neutrophils and macrophages exhibit this behavior as part of the body's immune response to infections or injuries.
Once they have exited the capillaries, leukocytes can take up fixed positions in organs like the lymphatic tissue, spleen, or thymus, or move through tissue spaces in an amoeba-like fashion. Their movement is directed by positive chemotaxis, which is a response to chemical signals emitted by cells at the infection site. This process essentially involves the leukocytes moving in response to the 'chemical 911 call' from the infected or injured cells. In clinical medicine, the presence and proportions of different types of leukocytes are important for diagnosis and treatment choices.
Emigration and Diapedesis
Emigration, synonymous with diapedesis, describes how leukocytes leave blood vessels to carry out their defensive functions in the body tissues. Different types of leukocytes, such as granular ones like eosinophils and neutrophils, and agranular ones like monocytes, which differentiate into macrophages, play distinct roles in immune defense, including the release of chemicals to destroy pathogens and performing phagocytosis.