Flax hypocotyl protoplasts were embedded in agarose and alginate heads
. The pectin molecules of the formed colonies were observed in electro
n microscopy using 2F4 antibody specific of a calcium-induced supramol
ecular conformation of homopolygalacturonic acid. Little pectin, mostl
y methylesterified, was present in agarose-entrapped colonies. The reg
enerating cells immobilized in alginate secreted much higher amounts o
f methylesterified pectins in their walls. De-esterification of the pe
ctins was clearly seen after 6 days of culture. These results illustra
te the importance of the external matrix on wall differentiation.