Cortical microtubules orientation

Shibaoka H. Plant hormone-induced changes in the orientation of cortical microtubules alterations in the cross-linking between microtubules and the plasma membrane. Ann Rev Plant Physiol Mol Biol 1994 45 527-544. 

Figure 23. Immunofluorescence micrographs in the aplanospore of 3h post-wounding of Boergesenia forbesii. Figure 23a is focused on the perinuclear microtubules, while Figure 23b is focused on the cortical microtubules which are oriented randomly.

Hasezawa, S. and Nozaki, H. 1999. Role of cortical microtubules in the orientation of cellulose microfibril deposition in higher-plant cells. Protoplasma 209, 98-104... 

Fig. 2.3 The development of polarity and asymmetric division in Saccharomyces cerevisiae. The diagram is reproduced in a slightly simplified form from the work of Lew Reed (1995) with the permission of Current Opinion in Genetics and Development, (a) The F-actin cytoskeleton strands = actin cables ( ) cortical actin patches, (b) The polarity of growth is indicated by the direction of the arrows (arrows in many directions signifies isotropic growth), (c) 10-nm filaments which are assembled to form a ring at the neck between mother and bud. (d) Construction of the cap at the pre-bud site. Notice that the proteins of the cap become dispersed at the apical/isotropic switch, first over the whole surface of the bud, then more widely. Finally, secretion becomes refocussed at the neck in time for cytokinesis, (e) The status and distribution of the nucleus and microtubules of the spindle. Notice how the spindle pole body ( ) plays an important part in orientation of the mitotic spindle.

In contrast with the single perinuclear MTOC present in most interphase animal cells, plant cells, polarized epithelial cells, and embryonic cells contain hundreds of MTOCs, which are distributed throughout the cell, often near the cell cortex. In plant cells and polarized epithelial cells, a cortical array of microtubules aligns with the cell axis. In both cell types, the polarity of the cell is linked to the orientation of the microtubules. 

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