Descendants of cells from region B are located within the splanchnic mesoderm and heart.

<p>(<b>A–B</b><b><i>i</i></b>) Sections from labelled stage HH11-12 embryos. (<b>A–B</b>) Sections at the level of the caudal pharynx showed that fluorescent descendants of cells from region B (red cells) were located in the splanchnic mesoderm and within the heart (ht). (<b>B–B</b><b><i>i</i></b>) Isl1 protein expression is indicated (green). Images were taken on a confocal microscope, <b>(C)</b> DAPI signal (blue) has been superimposed to provide a clearer picture of the morphology of the tissue. (<b>B</b><b><i>i</i></b>) Higher magnification of the boxed region in (<b>B</b>). Labelled cells located in the splanchnic mesoderm with DiI intercalated within the cell membrane express Isl1. Neural tube (nt), (n = 20). Scale bars (<b>A</b>) = 50 µm, (<b>B</b>) = 60 µm, (<b>B</b><b><i>i</i></b>) = 13 µm.