Polysaccharides storage site

Gums and mucilages may be found either in the intracellular pans of plants or as extracellular exudates. Those found within plant cells represent storage material in seeds and roots. They also serve as a water reservoir and as protection for germinating seed. The polysaccharides found as extracellular exudates of higher plants appear to be produced as a result of injury caused by mechanical means or by insects. It has not been well established whether the exudates are formed at the site of the injury. 

It is now many years since it was discovered that heparin is a constituent of the mast cell granule. Because it has been found in mast cells, many assume that this cell is the principal site of synthesis of this polysaccharide. However, there is evidence also that fibroblasts not only make hyaluronic acid, but possibly sulfated chondroitin polysaccharides as well. - There is not always a distinct correlation between the numbers of mast cells and the content of heparin of a particular tissue. The mast cell is found only in connective and reticular tissues. There is some evidence that mast cells in culture may synthesize heparin.However, another point of view has been put forward that the fibroblasts may make the polysaccharide and store it for a time and that, when they are full of these storage granules, they are called mast cells. ... 

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