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How do plasmodesmata differ from the apoplast in plant transport?
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cell wall
Cutaway drawing of a plant cell, showing the cell wall and internal organelles.
In plant transport, plasmodesmata and the apoplast represent two distinct pathways for the movement of molecules and water between cells.
- Plasmodesmata: These are microscopic cytoplasmic canals that penetrate cell walls to connect the cytoplasm of adjacent cells. They allow for the direct, internal communication and transport of molecules between neighboring protoplasts, effectively uniting plant cells into a continuous system.12
- Apoplast: This refers to the extracellular space between and within cell walls. It acts as a porous medium that allows for the free flow of water, minerals, and small nutrients around the outside of cells. Unlike the symplastic pathway provided by plasmodesmata, substances moving through the apoplast must cross the outer plasma membrane to enter a living protoplast.23
In summary, while plasmodesmata facilitate direct cell-to-cell transport through the interior of the plant, the apoplast serves as an external, extracellular network for the distribution of water and nutrients.123