Immunogold staining against EdU-Alexa488. 30 sec EdU pulse followed by 9 min (A–B) or 36 min (C–D) chase. At 9min chase, EdU labeled newly-replicated DNA (black, silver-enhanced gold particles) localizes at the immediate periphery of large-scale chromatin domains (grey) (A,B). After 36min chase (C,D), EdU pulse incorporation has spread within large-scale chromatin domains. Scale bars = 1 μm (A,C), 0.5 μm (B,D). See also Fig. S4.