Fig. 2. Spatiotemporal replication patterns in micronuclei after pulse-chase-pulse labelling with IdU and CldU (pulse, 30 minutes; chase, 2 minutes; pulse, 30 minutes). Mid optical sections of three successive micronucleus replication stages. To-Pro-3 was used for counterstaining. Columns 1-4 (from left) show fluorochrome channels that had been scanned sequentially, generating 8-bit greyscale images. Columns 5 and 6, false colours were assigned to each channel (Alexa Fluor 488^TM, green; Cy3, red; To-Pro-3, blue) before being overlaid. Replication patterns resemble type 1 [I, CldU (red); II, IdU (green)] and type 2 and/or type 3 [II, CldU (red); III, IdU (green)].