Preprophase

Preprophase is an additional phase during mitosis in plant cells that does not occur in other eukaryotes such as animals or fungi.

In gametophyte tissues during the reproductive phase of the plant life cycle, cell division planes may be established without the use of a preprophase band.

At the beginning of preprophase, the cortical microtubules of a plant cell disappear and aggregate into a dense ring underneath the plasma membrane.

[4] During progression from preprophase into prophase, the randomly oriented microtubules align parallel along the nuclear surface according to the spindle axis.

Experiments with drugs destroying microfilaments indicate that actin may play a role in keeping the cellular "memory" of the position of the division plane after the preprophase band breaks down to direct cytokinesis in telophase.

Microtubule dynamics during preprophase and prophase in plant cell mitosis, modified from Donukshe et al. [ 1 ] The images follow a tobacco BY-2 cell through the first stages of mitosis (c. 12 minutes). The growing ends of microtubules are shown in green (labeled with green fluorescent protein fused to the microtubule plus end binding protein EB1 of Arabidopsis thaliana ). N = Nucleus, V = Vacuole, PPB = Preprophase band, MTN = Microtubule nucleation starts at the nuclear envelope, NEB = Nuclear envelope breakdown at the onset of prometaphase . Also see the movie corresponding to this figure.