Name the first stage of mitosis, and describe what happens at this stage

The first stage of mitosis is ProphaseAt prophase...The already duplicated DNA within the nucleus condenses (coils up) to form sister chromatids, connected by a centromereThe nucleolus and nuclear envelope break down, releasing sister chromatids into the cytoplasmMitotic spindle fibres (made from microtubules) begin to form from the centrosome and extend towards the sister chromatids, ready to be used in metaphase