Proepicardial cells accumulate F-Actin. Optical section of 18 h in vivo time-lapse imaging of an epi:GFP;β-actin:LifeAct-RFP embryo starting at 52 hpf. GFP-labeled dorsal pericardium (DP) and proepicardial (PE) cells are shown in green. LifeAct-RFP marking F-actin is shown in red. Note that a subset of GFP+ cells accumulate LifeAct-RFP and, at the end of the video, are released into the pericardial cavity (arrow). The remaining GFP-positve DP cells reveal lower LifeAct-RFP intensity. HT, heart tube. Scale bar: 50 μm. Shown is a representative movie from ≥3 biological and ≥ 2 technical replicates.