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Fig. 6. Characterization of myocardial defects in Wnt11-R-depleted and JNK-inhibited embryos. (A) Whole mount immunostaining of unmanipulated st. 30 embryo showing activated JNK (p-JNK) in the heart region (arrow). (B) Transverse section through heart region of st. 30 embryo showing p-JNK-positive cells in the myocardial layer. (C) Transverse section through heart region of p-JNK-stained embryo. Arrowheads indicate regions of positive staining. (D) Nuclear staining with propidium iodide of same section shown in C illustrating the p-JNK localization is perinuclear. (E–H) Comparison of media control and JNK inhibitor (SP600125)-treated embryos at st. 33. (E and G) Whole mount in situ hybridization shows normal initiation of MHCα expression in treated and untreated embryos. (F and G) Transverse sections through the heart region of MHCα-stained embryos show that inhibition of JNK activation produces morphological defects in heart tube formation. (I–L) Transmission electron micrographs of transverse plastic sections through the myocardial wall from unmanipulated control and treated embryos at st. 33. In all panels, the endocardial side of the tube is to the right. Prominent dark spots are yolk granules. In all cases, spaces between adjacent cells have been colored in yellow. (I) Untreated control heart shows tightly packed columnar cells in myocardial wall with little space between adjacent cells. (J) Wnt11-R MO1-treated embryos show thickened wall of myocardium and increased extracellular space. (K) DMSO media-treated control hearts show very little space between adjacent cells in myocardium. (L) JNK inhibitor (SP600125)-treated embryos show increased thickness of myocardial layer and more extracellular space relative to DMSO-treated controls. |
