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In neuroscience, anterograde tracing is a research method which is used to trace axonal projections from their source (the cell body or soma) to their point of termination (the synapse). The complementary technique is ''retrograde tracing'', which is used to trace neural connections from their termination to their source (i.e. synapse to cell body). Both the anterograde and retrograde tracing techniques are based on the visualization of the biological process of axonal transport. The anterograde and retrograde tracing techniques allow the detailed descriptions of neuronal projections from a single neuron or a defined population of neurons to their various targets throughout the nervous system. These techniques allow the "mapping" of connections between neurons in a particular structure (e.g. the eye) and the target neurons in the brain. Much of what is currently known about connectional neuroanatomy was discovered through the use of the anterograde and retrograde tracing techniques.〔 ==Techniques== Several methods exist to trace projections originating from the soma towards their target areas. These techniques initially relied upon the direct physical injection of various visualizable tracer molecules (e.g. Green fluorescent protein, lipophylic dyes or radioactively tagged amino acids) into the brain. These molecules are absorbed locally by the soma (cell body) of various neurons and transported to the axon terminals, or they are absorbed by axons and transported to the soma of the neuron. Other tracer molecules allow for the visualization of large networks of axonal projections extending from the neurons exposed to the tracer.〔 Over the recent years viral vectors have been developed and implemented as anterograde tracers to identify the target regions of projecting neurons. Alternatively strategies are transsynaptic anterograde tracers, which can cross the synaptic cleft, labeling multiple neurons within a pathway. Those can also be genetic or molecular tracers. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「anterograde tracing」の詳細全文を読む スポンサード リンク
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