Mitosis- Metaphase

By Tessa

Metaphase is the next stage of mitosis. First, the nuclear membrane disappears completely. In animal cells, the pairs of centrioles align themselves along at opposite poles of the cell. Polar fibers, which are microtubules contained in the spindle fibers, keep on extending from the poles to the center of the cell. The chromosomes move around in a random way until they connect (with their kinetocheres) to the polar fibers from each side of their centromeres. When the spindle attaches to both sister chromatids, the chromosomes are aligned perpendicularly. Metaphase is usually the most time-consuming stage of mitosis. This is because it can take a while for the chromosomes to be perfectly alligned.

Sources:

About.com had detailed info on each phase. Click here to go there, but the language can be somewhat confusing.

This is a site that simplifies some of the harder concepts, by University of California San Francisco. Not much detail though.