cells, or "exophers," released by nematode neurons and mouse cardiomyocytes. Exosomes: membranous vesicles of endocytic origin (30-100 nm diameter). Different types of EVs may be separated based on density (by gradient differential centrifugation), size, or surface markers. However, EV subtypes have an overlapping size and density ranges, and subtype-unique markers must be established on a cell-by-cell basis. Therefore, it is difficult to pinpoint the biogenesis pathway that gave rise to a particular EV after it has left the cell. In humans, endogenous extracellular vesicles likely play a role in coagulation, intercellular signaling and waste management. They are also implicated in the pathophysiological processes involved in multiple diseases, including cancer. Extracellular vesicles have raised interest as a potential source of biomarker discovery because of their role in intercellular communication, release into easily accessible body fluids and the resemblance of their molecular content to that of the releasing cells. The extracellular vesicles of (mesenchymal) stem cells, also known as the secretome of stem cells, are being researched and applied for therapeutic purposes, predominantly degenerative, auto-immune and/or inflammatory diseases. In Gram-negative bacteria, EVs are produced by the pinching off of the outer membrane; however, how EVs escape the thick cell walls of Gram-positive bacteria, mycobacteria and fungi is still unknown. These EVs contain varied cargo, including nucleic acids, toxins, lipoproteins and enzymes and have important roles in microbial physiology and pathogenesis. In host-pathogen interactions, gram negative bacteria produce vesicles which play roles in establishing a colonization niche, carrying and transmitting virulence factors into host cells and modulating host defense and response. Ocean cyanobacteria have been found to continuously release vesicles containing proteins, DNA and RNA into the open ocean. Vesicles carrying DNA from diverse bacteria are abundant in coastal and open-ocean seawater samples. Other types Gas vesicles are used by Archaea, bacteria and planktonic microorganisms, possibly to control vertical migration by regulating the gas content and thereby buoyancy, or possibly to position the cell for maximum solar light harvesting. These vesicles are typically lemon-shaped or cylindrical tubes made out of protein; their diameter determines the strength of the vesicle with larger ones being weaker. The diameter of the vesicle also affects its volume and how efficiently it can provide buoyancy. In cyanobacteria natural selection has worked to create vesicles that are at the maximum diameter possible while still being structurally stable. The protein skin is permeable to gasses but not water, keeping the