What is the term for the fusion of a vesicle with the plasma membrane to release contents outside the cell?

The term for the fusion of a vesicle with the plasma membrane to release contents outside the cell is exocytosis. In this process, cellular material such as hormones, neurotransmitters, or waste products is packaged in vesicles that then merge with the plasma membrane. This fusion allows the vesicle contents to be released into the extracellular space.

Exocytosis is crucial for various cellular functions, including communication between cells, the secretion of substances, and the removal of unwanted materials. It is a common mechanism utilized by cells to expand their membrane surface area or to modulate their environment.

This process is distinct from endocytosis, where materials are brought into the cell, and does not involve the active transport of substances across the membrane in the same way that active transport does. Additionally, transcytosis refers to the transport of molecules across the interior of a cell through vesicular transport, rather than the direct fusion of vesicles with the plasma membrane to release their contents. Therefore, the correct term that describes the process of releasing contents outside the cell through vesicle fusion is indeed exocytosis.