Fig. 2. Gata4 deficient embryos develop cardiac and gut tubes but no derivative organs. (A-C) Shown at 3 dpf are (A) a representative control embryo (WT), and embryos derived from eggs injected with (B) the morpholino targeting the Gata4 5'UTR (MO) or (C) the morpholino targeting an intron/exon boundary (MO1). The morphant fish display a kink in the tail (white arrowheads), a pericardial edema (black arrows), and regression of the yolk stalk extension (black arrowheads). (D,E) Control embryo (D) and a representative morphant (E), showing a relative lack of blood in the linear but constricted heart tube at 3 dpf in the morphant (red arrow). (F) At 5 dpf, the morphant linear heart tube (red arrow) is distended. Views are lateral, dorsal to the top and anterior to the right. (G) At 8 dpf, a linear gut tube is shown (arrow), running the length of the morphant body. (H-M) Representative histological cross sections through control (WT) or morphant (MO) embryos. Equivalent sections are progressively more caudal, at the level of the heart (H,K), mid-pancreas (I,L) or the caudal end of the swim bladder (J,M). A, atrium; V, ventricle; HT, heart tube; P, pancreas; L, liver; I, intestine; Y, yolk.