Morphogenetic fields
<p>In <a href="http://en.wikipedia.org/wiki/Developmental_biology" title="Developmental biology" >developmental biology</a>, a <b >morphogenetic field</b> is a group of <a href="http://en.wikipedia.org/wiki/Cell(biology)" title="Cell (biology)" >cells</a> able to respond to discrete, localized <a href="http://en.wikipedia.org/wiki/Biochemical" title="Biochemical" class="mw-redirect" >biochemical</a> signals leading to the development of specific morphological structures or <a href="http://en.wikipedia.org/wiki/Organ(anatomy)" title="Organ (anatomy)" >organs</a>.<sup id="cite_ref-MBOC_1-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Morphogenetic_field#cite_note-MBOC-1" >[1]</a></sup><sup id="cite_ref-2" class="reference" ><a href="http://en.wikipedia.org/wiki/Morphogenetic_field#cite_note-2" >[2]</a></sup> The <a href="http://en.wiktionary.org/wiki/spatial" class="extiw" title="wikt:spatial" >spatial</a> and <a href="http://en.wiktionary.org/wiki/temporal" class="extiw" title="wikt:temporal" >temporal</a> extent of the embryonic fields are dynamic, and within the field is a collection of interacting cells out of which a particular organ is formed.<sup id="cite_ref-Gilbert_1996_3-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Morphogenetic_field#cite_note-Gilbert_1996-3" >[3]</a></sup> As a group, the cells within a given morphogenetic field are constrained — i.e. cells in a<i >limb field</i> will become a limb tissue, those in a <i ><a href="http://en.wikipedia.org/wiki/Cardiac" title="Cardiac" class="mw-redirect" >cardiac</a> field</i> will become heart tissue.<sup id="cite_ref-Gilbert_2003_4-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Morphogenetic_field#cite_note-Gilbert_2003-4" >[4]</a></sup> Importantly, however, the specific cellular programming of individual cells in a field is flexible: an individual cell in a cardiac field can be redirected via cell-to-cell signaling to replace specific damaged or missing cells.<sup id="cite_ref-Gilbert_2003_4-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Morphogenetic_field#cite_note-Gilbert_2003-4" >[4]</a></sup><a href="http://en.wikipedia.org/wiki/Imaginal_disc" title="Imaginal disc" >Imaginal discs</a> in insect <a href="http://en.wikipedia.org/wiki/Larva" title="Larva" >larvae</a> are examples of morphogenetic fields.<sup id="cite_ref-MBOC2_5-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Morphogenetic_field#cite_note-MBOC2-5" >[5]</a></sup>
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