Figure 6
Pharyngeal arch tissues induce differentiation of amniogenic somatopleural cells into vascular endothelial cells and cardiomyocytes, possibly via FGF and BMP signaling, respectively. (a–r) Amniogenic somatopleural explants from quail embryos at 9ss to 11ss are co-cultured with chick first and second pharyngeal arch (pa1/pa2) explants at HH15 and immunostained for QH1 and cytokeratin (a–i) or QCPN and cardiomyocyte marker cardiac troponin I (cTnI) (j–r). (a–i) Quail somatopleural explants alone do not show QH1-positive endothelial cells (n = 7) (a–c). By contrast, co-culture with pharyngeal arch explants induces endothelial cell differentiation (n = 7) (d–f), which is inhibited by FGF receptor antagonist SU5402 (20 µM) (n = 7) (g–i). (j–r) Although quail somatopleural explants alone do not show cTnI-positive cardiomyocytes (n = 3) (j–l), co-culture with pharyngeal arch explants induces cardiomyocyte differentiation (n = 3) (m–o), which is inhibited by Noggin (500 ng/ml), a BMP antagonist (n = 4) (p–q). TO-PRO-3 is used to counterstain nuclei. Scale bars, 20 µm.
