Fig. 3

Ventricular cardiomyocytes can exit the heart tube in Cyp26-deficient embryos.

(A,B) 30-min interval frames from confocal time-lapse movies of control and Cyp26-deficient Tg(myl7:EGFP) hearts. Images of hearts were depth-coded with the spectrum ranging from pink at 120 μm to blue at 0 μm. (C,D) Hematoxylin–eosin (HE) stained frontal sections of the hearts from control and Cyp26-deficient embryos. Endocardium (white arrowheads) and myocardium (black arrowheads). Control hearts n = 4. Cyp26-deficient hearts n = 5. (E,F) Control and Cyp26-deficient Tg(myl7:EGFP);Tg(kdrl:mCherry) embryos at 48 hpf. Endocardium (red) and myocardium (green). Arrowheads indicate the inner border of endocardial and outer border of myocardial cells. (G) Graph showing the distance between the endocardial and myocardial layers (control n = 5, Cyp26 deficient n = 7). (H–I”‘) Confocal images of control and Cyp26-deficient Tg(myl7:EGFP) hearts stained for zonula occludens 1 (ZO1) (red) and green fluorescent protein (GFP) (green), with schematized outlines of cell boundaries and ZO1 staining. Arrow denotes cardiomyocyte protruding into the pericardial space. (J) Graph depicting the percentage of ZO1 expression along the height of cardiomyocytes (control n = 15, Cyp26 deficient n = 15). (K) Graph depicting circularity measurement of ventricular cells (control n = 15, Cyp26 deficient n = 30). (L–M''') Confocal images of control and Cyp26-deficient Tg(myl7:EGFP) hearts stained for β-catenin (red) and GFP (green), with schematized outlines of cell boundaries and β-catenin staining. Error bars are SEM, asterisk denotes p < 0.05 by Student’s t test. Frontal views, anterior up (A–F,H,I,L,M); n > 20 embryos per group (E,F,H,I,L,M). A, apical; B, basal. Scale bar for C–M’: 50 μm. Scale bar for H''–M''': 25 μm.