Source:http://linkedlifedata.com/resource/umls/id/C1450355
NCI: A phase of mitosis occurring between prophase and metaphase. During this phase the nuclear envelope disappears and the spindle development continues as spindle microtubules attach to either chromosomal kinetochore complexes or opposing microtubules.,MSH: The phase of cell nucleus division following PROPHASE, when the breakdown of the NUCLEAR ENVELOPE occurs and the MITOTIC SPINDLE APPARATUS enters the nuclear region and attaches to the KINETOCHORES.