Prophase is the stage in the cell cycle that is known for the condensation and disappearance of the nucleolus. In this stage chromosome become more compacts and the sister chromatids are still together and not separated. These sister chromatids are joined together with the centromere.
Centromere do not allow sister chromatids to move away and makes it intact. The number of centromere is the number of chromosme present in the prophase and half of the sister chromatids that means if there us 3 centromere than the number of sister chromatids will be 6.
