What occurs in the first stage of mitosis

The first stage is prophase → nuclear division begins (the nucleus begins to split in two) – nuclear membrane dissipates → chromosomes condense and become visible – appear as double stranded → the nucleolus shrinks (nucleolus produces and forms ribosomes – found in the nucleus) → centrioles move to opposite sides of the cell → spindle microtubules or fibres form between the two centrioles – spindle fibres are made of contractile proteins