Final answer:
Leukocytes release the contents of their cytoplasmic granules through a process called exocytosis, which aids in immune response by attacking pathogens. Diapedesis, also known as emigration, involves leukocytes squeezing through blood vessel walls to reach infection sites. Histamine secretion by mast cells is another example of a regulated secretion in response to foreign pathogens.
Step-by-step explanation:
When leukocytes release the contents of their cytoplasmic granules, the process is called exocytosis. Granular leukocytes, such as neutrophils, eosinophils, and basophils, contain abundant granules within their cytoplasm that are packed with chemicals capable of destroying pathogens. During exocytosis, these granules fuse with the cell membrane, releasing their contents into the extracellular space to help fight off infections. This plays a crucial role in the body’s immune response by directly attacking pathogens or flagging them for destruction by other immune cells.
Another related process is diapedesis or emigration, in which leukocytes squeeze through adjacent cells in a blood vessel wall to enter tissues. This is part of the immune response where leukocytes move towards the site of infection or injury.
The process by which secretory vesicles release their contents is a form of regulated secretion found in various cells, including those of the immune system such as mast cells which secrete histamine.