Simple Italian Microscope (circa 1686)


Galleria
License Info
Image Use
Custom Photos
Partners
Site Info
Contact Us
Publications
Home

The Galleries:

Photo Gallery
Silicon Zoo
Pharmaceuticals
Chip Shots
Phytochemicals
DNA Gallery
Microscapes
Vitamins
Amino Acids
Birthstones
Religion Collection
Pesticides
BeerShots
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery
 

Plasmodesmata

Plasmodesmata (singular, plasmodesma) are small channels that directly connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cells. Similar to the gap junctions found in animal cells, the plasmodesmata, which penetrate both the primary and secondary cell walls (see Figure 1), allow certain molecules to pass directly from one cell to another and are important in cellular communication.

Plasmodesma Intercellular Junction

The plasmodesmata is structured in an entirely different configuration than the animal cell gap junction because of the thick cell wall. Due to the presence of plasmodesmata, plant cells can be considered to form a synctium, or multinucleate mass with cytoplasmic continuity. Accordingly, the tiny channels have caused a significant amount of debate among scientists regarding cell theory, some suggesting that the cells of higher plants are not really cells at all since they are not physically separated or structurally independent from one another.

Somewhat cylindrical in shape, plasmodesmata are lined with the plasma membrane so all connected cells are united through essentially one continuous cell membrane. A majority of plasmodesmata also contain a narrow tube-like structure called the desmotubule, which is derived from the smooth endoplasmic reticulum of the connected cells. The desmotubule does not completely fill the plasmodesma and, consequently, a ring of shared cytoplasm is located between it and the inner surface of the membrane-lined channel. Plasmodesmata typically form during cell division when parts of the endoplasmic reticulum of the parent cell get trapped in the new cell wall that is produced to create daughter cells. Thousands of plasmodesmata may be formed that connect the daughter cells to one another.

It is widely thought that by constricting and dilating the openings at the ends of the plasmodesmata, plants cells regulate the passage of small molecules, such as sugars, salts, and amino acids, though this mechanism is not yet well understood. Yet, it is known that in some cases the size restrictions on molecule passage between cells can be overcome. By binding to parts of the plasmodesmata, special proteins and some viruses are able to increase the diameter of the channels enough for unusually large molecules to pass through.

BACK TO PLANT CELL STRUCTURE

Questions or comments? Send us an email.
© 1995-2022 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, software, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Friday, Nov 13, 2015 at 02:18 PM
Access Count Since October 1, 2000: 337505
Microscopes provided by:
Visit the Nikon website. Visit the Olympus Microscopy Resource Center website.