the membrane (kiss-and-run fusion) via porosome. Non-constitutive exocytosis and subsequent endocytosis are highly energy expending processes, and thus, are dependent on mitochondria. Examination of cells following secretion using electron microscopy demonstrate increased presence of partially empty vesicles following secretion. This suggested that during the secretory process, only a portion of the vesicular content is able to exit the cell. This could only be possible if the vesicle were to temporarily establish continuity with the cell plasma membrane at porosomes, expel a portion of its contents, then detach, reseal, and withdraw into the cytosol (endocytose). In this way, the secretory vesicle could be reused for subsequent rounds of exo-endocytosis, until completely empty of its contents. See also Endocytosis Pinocytosis Phagocytosis Membrane nanotube Viral shedding Presynaptic active zone Residual body Degranulation References External links Cellular processes Neurophysiology Membrane biology