Explanation

The complete disintegration of the nuclear envelope marks the start of the second phase of mitosis, i.e., metaphase. Hence the chromosomes are spread through the cytoplasm of the cell. By this stage, condensation of chromosomes is completed and they can be observed clearly under the microscope. This then, is the stage of which morphology of chromosomes is most easily studied. At this stage, metaphase chromosomes are made up of two sister chromatids, which are held together by the centromere