Pectins constitute a diverse class of galacturonic acid-rich polysaccharides, which can be classified into three main domains: the homogalacturonans, the rhamnogalacturonan I, and the rhamnogalacturonan II. The HGAs are linear homopolymers of -a-linked-D-galacturonic acid with 100�C200 GalA residues, which present variation in their degree of methyl-esterification, and correspond to approximately 65% of the total cell wall pectins. The RG-I represents 20�C35% of the pectic Ursolic-acid matrix and is an alternate form of HGAs, which has many structurally different side chains a ached via C-4 of the backbone rhamnosil, with arabinosyl and galactosyl residues as the predominant components of the chains. The RG-II is structurally more complex, comprising about 10% of the total pectins in cell matrix. The variation in the Forsythin methyl-esterification of all these components results in divergence of their physical states, which alters the functional properties of plant cell wall, especially during the growth and development of plant tissues, which can be addressed in the cell walls of insect galls. The site of the synthesis of pectins is the Golgi lumen, but how their synthesis are initiated remains unclear. Their demethylesterificaton, however, , such as the pectin methylesterases, which are encoded by multiple genes classified either as type I or type 2, depending on the presence of a PME inhibitor or a signal pepitide for secretion. For co on fibres, for instance, the two most expressed genes were correlated with the total amount of enzyme activity and de-esterification of pectins at late stages of development. This correlation was observed either biochemically or immunocitochemically. The immunocitochemical labeling of HGAs and RGs with monoclonal antibodies in the cells of insect-induced plant galls may constitute an elegant tool to demonstrate the relationship between pectin distribution and its biological functions at the level of cells and tissues as proposed by Verhertbruggen et al. for plant organs, in general. Also, this kind of analysis can be considered usefull for understanding the pa erns of PMEs activity. Together with the HGAs and RGs, structural and highly soluble glycosylated proteins, the arabinogalactan proteins, are associated with the cell wall or the plasmalemma. The AGPs are a class of the hydroxyl-proline-rich glycoprotein family that have mucilaginous appearance and are also involved in cell adhesion, plant development, growth, nutrition, cell proliferation, and prevention of programmed cell death. They form a gel plug in sites of cell injury constituting a physical barrier to cell invasion, specifically by the glycosylation of -b-galactans and -a-arabinans. The galls on Baccharis dracunculifolia, as a model of study of subcellular responses to external stimuli, is evaluated by the comparison of the current results with those presented for B. reticularia. On B. reticularia, the pectin distribution was studied in three distinct gall morphotypes only in mature phase, while herein we analyse a single and similar morphotype on developmental basis. Current study is based on the premise that pectins are important in the determination of the new shape and functionality of plant galls, which develop through highly specific and repetitive cell cycles, and present well-marked developmental phases.