Expression of orthologs of bilaterian mesodermal genes that are broadly expressed in <i>I. Pulchra.</i>

<p>In the left panel whole-mount <i>in situ</i> hybridization of juvenile (left column) and adult (central and right columns) specimens are shown. Expression in the specimens in the right column is detected with fluorescent signal (purple). The arrow points to the female genital organ, arrowhead to the male genital organ. The asterisk indicates the cross parenchymal muscles. In the right panel the neoblasts localization of the transcript is shown. Left columns all show double stained worms with EdU and with the fluorescent antisense probe. The center and right columns show RNA transcripts and neoblasts staining alone. All aspects show a single confocal plane. The empty arrowheads point to colocalized EdU-RNA signal. Anterior to the left, scale bar 50 µm in all aspects<b>. A–F</b>. <i>IpmuscleLIM</i> expression. hm: head myocytes; nb/go: neoblasts and gonads pa:parenchymal cells; ds: digestive syncytium. <b>D–L</b>. <i>IpPitx</i> expression. The mouth is surrounded by specialized ring muscles (m) that express <i>IpPitx</i> (<b>H</b> and <b>I</b>). <b>M–R </b><i>IpFoxA1</i> expression. <i>IpFoxA1</i> is expressed in the endodermal digestive syncytium (ds) as well as in the mesodermal musculature (<i>e.g.</i>, the mouth ring muscles, <b>N</b>). The black empty arrowheads in <b>M</b> and <b>N,</b> show paired muscles associated to the copulatory organs. <b>S–X</b>. <i>IpFoxC</i> expression.