Metaphase

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metaphase

[′med·ə‚fāz]
(cell and molecular biology)
The phase of mitosis during which centromeres are arranged on the equator of the spindle.
The phase of the first meiotic division when centromeric regions of homologous chromosomes come to lie equidistant on either side of the equator.

Metaphase

 

one of the stages of mitotic cellular division.

Two periods of metaphase are distinguished. The first is metakinesis, during which the chromosomes concentrate in the equatorial region of the spindle and form what is called the equatorial plate. There are a number of hypotheses regarding the mechanism of metakinesis; the trajectories of the chromosomes have been described, and maps have been drawn of the paths of the centromeres and arms of the chromosomes.

The second period of metaphase is metaphase proper, during which links are established between the chromosomal threads of the spindle and the centromeres, the chromosomes separating into chromatids. Metaphase lasts from 0.3 to 175 min in different cells. In meiosis the analogous stage of the first division is called metaphase I.