Dynamic expression of brachial <i>Hox</i> genes in the spinal cord.

<p>(A) Expression of Hoxc6 and FoxP1 in LMC neurons between e10.5 and e13.5. Images show ventral quadrant of the spinal cord and LMC neurons are identified by FoxP1 expression. Hoxc6 protein is detected in postmitotic MNs but not in MN progenitors (pMNs). At e10.5 Hoxc6 is expressed by FoxP1+ LMC neurons but by e12.5 is attenuated in most LMC neurons. (B) Grayscale images showing progressive decline in Hoxc6 protein expression from LMC neurons. (C–J) Expression of <i>Hox4–Hox8</i> paralogs at brachial levels of the spinal cord. <i>Hoxb6</i> and <i>Hoxb7</i> are expressed in pMNs. (K) Summary of Hox expression patterns. Hoxc4, Hoxa5, Hoxc6 expression domains extend further rostrally in the spinal cord and are not shown. Hoxa7 and Hoxc8 expression also extends into thoracic levels, indicated in light grey.