There is a constant and rapid flux of vesicles fusing with the plasma membrane, this dynamic process is known as exocytosis. 

Exocytosis is crucial for several cellular functions, such as the secretion of hormones, enzymes, or neurotransmitters, as well as the incorporation of new membrane components. This process is particularly important in diverse biological processes, including cell signaling, immune response, and the release of neurotransmitters.

Granule Secretion

Granule secretion is a vital cellular process in which the contents of vesicles are released in response to external stimuli. This physiological process is crucial for proper immune responses, neural communication, and homeostasis.

 The content of granules can be fluorescently labeled to detect granule secretion. Notice in the image to the right how the intensity and diameter of the vesicle increase as the granule secretion progresses from inital secretion (a), reaching a maximum (b), and finally distribution (image c).


Large Field of View Granule Secretion

The contents of granules are fluorescently labeled. While several granules are docked close to the plasma membrane, appearing as lingering punctate structures, others fuse to release their content into the extracellular space. Not all cells are actively undergoing granule secretion, highlighting the advantages of a large field of view. Images were acquired using a 60x objective. The scale bar is 40 μm


Reveal Varied Activity Across Distinct Regions

Cells with high activity. Scale bar 10: μm


Cells With medium activity. Scale bar: 10 μm


Cells With Low Activity. Scale bar: 10 μm


Dynamics of Exocytic Events: Diverse Approaches to Visualization

Notice the difference between exocytic events involving the release of fluorescent content (left) and fluorescent proteins that mediate vesicle fusion (right). The image series on the left shows the content as it is secreted out of the vesicle, while on the right, the content is not visible; instead, fluorescently tagged proteins diffuse along the plasma membrane, soon to be recycled.


Low magnification TIRF exocytosis

Exocytosis is a dynamic cellular mechanism central to intercellular communication, and entails the regulated release of cellular contents. In addition to visualizing the released content, as demonstrated above, it is also possible to investigate the kinetics of various proteins involved in the fusion event, providing insights into the temporal aspects of exocytosis. Below is an example of a fluorescently labeled protein crucial for the fusion between vesicles and the plasma membrane. The scale bar is 100 μm.