Why are the chromosomes changed into long, fine chromatin fibres in the interphase?

The chromosome first appear as long, thin tetrad in the nucleus. At this stage, the cheomosomes overlap and have invisible ends. The chromosome gradually change into short, thick rods and become visible. The changes occur by loss of water and progressive coiling of chromosomes. The progressive folding and packing reduces them to 4% of their original length. Due to the change, the chromosome appears long, fine chromatin fibres.