During prophase,
the chromatin condenses and the chromosomes become visible. Also the nucleolus
disappears, the nuclear membrane fragments, and the spindle appartus forms
and attaches to the centromeres of the chromosomes. These are dividing cells
in the roor tip of an onion plant. Early and late prophase can be seen.
In late prophase, the
chromatin has condensed into chromosomes, the nucleolus is gone, and the nuclear
envelope has been removed.