Visualizing large chromosomal regions using FISH probes and analysis of FISH signals. (A) Chromosomal (Chr) location of euchromatin (Eu) and heterochromatin (Het) FISH probes used in this study. (B) Dual-color FISH showing the nuclear appearance and location of two heterochromatin and euchromatin probes. (C) Steps for generating skeleton dot images and calculating skeleton dot lengths. (D) An example outcome of executing the steps in C. Macro was created and executed using Fiji. Scale bar for B = 5 µM; for D = 2 µm.