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A distinction is sometimes made between paracrine and autocrine signaling. Both affect neighboring cells, but whereas autocrine signaling occurs among the same cell, paracrine signaling affects other cells. Two neurons would be an example of a paracrine signal.
Some signaling molecules degrade very quickly, limiting the scope of their effectiveness to the immediate surroundings. Others affect only nearby cells because they are taken up quickly, leaving few to travel further, or because their movement is hindered by the extracellular-matrix.
Growth factor and clotting factors are paracrine signaling agents. The local action of growth factor signaling plays an especially important role in the development of tissues. In insects, Allatostatin controls growth though paracrine action on the corpora allata.
The overproduction of certain paracrine growth factors has been implicated in the pathology of cancer.
Autocrine and endocrine actionsEdit
For example, testosterone secreted from the testes acts as an endocrine agent to stimulate peripheral events, such as muscle growth, and as a paracrine agent to stimulate spermatogenesis in the adjacent seminiferous tubules.
- MeSH Paracrine+Signaling
- Dictionary at eMedicine Paracrine
- GPnotebook -1335164869
Cell physiology: cell signaling
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