Fig. 2
Cardiomyocytes extend protrusions luminally while still in the compact layer. (A) Illustration of the orientation of the hearts shown in B and C. (B) Optical slice of a 60 hpf Tg(myl7:ras-GFP) heart with cardiomyocytes marked with multiple fluorescent proteins. Arrow points to a marked cellular protrusion (red), extending over another marked cardiomyocyte (purple). (B2) View of the same dataset as B rotated 90°, showing that this protrusion extends from a cardiomyocyte that is still mostly contained within the compact layer. (C) Optical slice of a 78 hpf Tg(myl7:EGFP) heart similarly marked with multiple fluorescent proteins. Arrow points to a protrusion extending from a trabecular cardiomyocyte (green). (C2) View of the same dataset as C rotated 90°, showing that the same cardiomyocyte extends multiple protrusions. AVC, atrioventricular canal; IC, inner curvature; OC, outer curvature; OFT, outflow tract. Scale bars: 10 μm.