A "MICROTUBULE" IN PLANT CELL FINE STRUCTURE

Area of Science:

• Plant Cell Biology
• Cellular Ultrastructure
• Cytoskeleton Dynamics

Background:

• Previous studies using osmium tetroxide (OSO(4)) fixation showed plasma membrane discontinuities in plant cells during wall formation.
• Inadequate fixation methods limited the understanding of cortical fine structure and cellular processes.

Purpose of the Study:

• To investigate the ultrastructure of plant cell cortices using improved fixation techniques.
• To identify and characterize novel cellular structures potentially involved in cell wall formation and cytoplasmic streaming.

Main Methods:

• Electron microscopy was employed to examine plant cell cortices.
• Glutaraldehyde was used as a primary fixative, improving the preservation of cellular fine structure compared to OSO(4) alone.

Main Results:

• Glutaraldehyde fixation revealed slender tubules (230-270 A diameter) in the cortical regions of angiosperm and gymnosperm cells.
• These tubules were also observed in mitotic spindles, albeit with a slightly smaller diameter.
• Cortical tubules were found to be positioned near the plasma membrane and their orientation appeared to correlate with adjacent cellulose microfibril alignment.

Conclusions:

• Improved glutaraldehyde fixation provides enhanced visualization of plant cell cortical structures.
• The newly identified cortical tubules may play a role in regulating cytoplasmic streaming and directing cell wall material deposition.
• The observed correlation between tubule orientation and cellulose microfibrils suggests a potential role in cell wall organization.