Biology Reference
In-Depth Information
FIGURE 23.14
The succession of orientated cell divisions in the early development of the embryo of Capsella
bursa-pastoris ('Shepherd's purse'): the orientation of each cell division is shown by the arrow above it, in the top of
the diagram. Based on Fahm.
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In the schizoriza mutant of A. thaliana, the pattern of division is disrupted so that there is
more than one periclinal division before anticlinal division begins. Because each periclinal
division produces daughter cells aligned along a radius, the effect of this disrupted division
pattern is to produce an arc of cells more than one cell thick (
Figure 23.16
). The genetics and
cell biology of the mutant are complicated (differentiation is affected as well),
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but the exis-
tence of a single mutant that has the effect of disrupting orientation of cell division underlines
the basic fact that orientation of cell division is under strict control.
FIGURE 23.15
Nomenclature for division planes in the root tip.
