Figure 4
Amniogenic somatopleural cells differentiate into vascular endothelial cells and cardiomyocytes. (a–k) Dye-labeling in quail embryos. DiI is injected onto the amniogenic somatopleure adjacent to the head fold in a quail embryo at 10ss (red arrowhead) (a). Schematic depiction is superimposed. (b) Forty-eight hours after DiI injection (equivalent to HH18+), dye-labeled cells distribute to the amnion, the first pharyngeal arch, the outflow tract and pericardium. Yellow arrowheads indicate distribution of DiI in the embryonic tissues. (c–k) Immunostaining of transverse sections of the embryo shown in (b) at different levels. Boxes in (c,f,i) are magnified in (d, e), (g, h) and (j, k), respectively. DiI-labeled cells are detected in the QH1-positive vascular endothelium in the first pharyngeal arch (c–e) and myosin heavy chain (MHC)-positive myocardium in the outflow tract (f–k). (l–q) Quail-chick chimera experiments. A quail amniogenic somatopleure graft is orthotopically transplanted into the chick somatopleure at 10ss (l). The graft is visualized by DiO-labeling (white arrowhead). (m–q) Immunostaining of transverse sections of the recipient embryo after 48 hours. Boxes in (m,o) are magnified in (n) and (p, q), respectively. QH1- or QCPN-positive quail cells (white arrowheads) are detected in the von Willebrand factor (vWF)-positive vascular endothelium in the first pharyngeal arch (m,n) and MHC-positive myocardium in the outflow tract (o–q). TO-PRO-3 is used to counterstain nuclei. nt, neural tube; oft, outflow tract; pa1, first pharyngeal arch; pa2, second pharyngeal arch; th, thoracic wall. Scale bars, 100 µm for (f,i,m,p), 20 µm for others.
