Organization and migration of MES epithelial cells in MES trails. Confocal live imaging of GFP expression in E15.5 CrectTg/0; R26mTmG/+ secondary palate sagittal section shows MES trail movement as MES cells join the nasal epithelium and breakage of a trail to form an epithelial island. Arrowheads point to trails and broken ends of a trail. Images were captured every 15 minutes for 20 hours. Scale bar, 20μm.