And the number of English language learners has increased by 65 percent between 1993 and 2004 compared to barely a 7 percent increase in the total K12 population, according to a 2006 study by the National Clearinghouse for English Language Acquisition.
Exocytosis. Photo by: Alila. Exocytosis is the cellular process in which intracellular vesicles in the cytoplasm fuse with the plasma membrane and release or secrete their contents into the extracellular space. Exocytosis can be constitutive (occurring all the time) or regulated. Constitutive exocytosis is important in transporting proteins like receptors that function in the plasma membrane. Regulated exocytosis is triggered when a cell receives a signal from the outside.
Exocytosis. 1  The process by which vesicles inside the cell fuse with the cell membrane and release their contents into the synaptic cleft is called exocytosis. 2  The cycle of exocytosis is as follows: First a vesicle approaches the membrane, on its way to an activate site. The influx of calcium during depolarization of the endfoot appears to activate a system of microtubules within the endfoot. 2  The microtubules exert mechanical force and induce the movement of vesicles toward the presynaptic membrane. 3  The vesicles then eject neurotransmitter into the synaptic cleft.