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The secondary cell wall is a structure found in many plant cells, located between the primary cell wall and the plasma membrane.The cell starts producing the secondary cell wall after the primary cell wall is complete and the cell has stopped expanding. [1]
In plants, a secondary cell wall is a thicker additional layer of cellulose which increases wall rigidity. Additional layers may be formed by lignin in xylem cell walls, or suberin in cork cell walls.
Neighbouring plant cells are therefore separated by a pair of cell walls and the intervening middle lamella, forming an extracellular domain known as the apoplast. Although cell walls are permeable to small soluble proteins and other solutes , plasmodesmata enable direct, regulated, symplastic transport of substances between cells.
The pit aperture is the opening at either end of the pit chamber. The pit membrane is the primary cell wall and middle lamella, or the membrane between adjacent cell walls, at the middle of the pit chamber. [2] The primary cell wall at the pit membrane may also have depressions similar to the pit depressions of the secondary layers.
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
Collenchyma cells are usually living, and have only a thick primary cell wall [6] made up of cellulose and pectin. Cell wall thickness is strongly affected by mechanical stress upon the plant. The walls of collenchyma in shaken plants (to mimic the effects of wind etc.), may be 40–100% thicker than those not shaken.
These are sclerenchyma cells which generally fall into two categories: fibres and sclereids. Both cell types have a secondary cell wall and are dead at maturity. The secondary cell wall increases their rigidity and tensile strength, especially because they contain lignin.
Young shoots are often eaten by animals because the fibers in the new growth have not yet completed secondary cell wall development, making the young shoots softer and easier to chew and digest. As shoots grow and age, the cells develop secondary cell walls that have a hard and tough structure.