Pollens appear like a fine to coarse powder that is liberated by the
microsporangia of Gimnosperms and Angiosperms. The pollen grain wall,
the sporoderm, envelopes the microgametophytes (male gametophytes),
which produce the male gametes of seed plants. Pollen grains are
interesting from the material science point of view since the native
polymer, the sporopollenin, found in the sporoderm outer layer (exine),
is one of the toughest known materials which is degraded by oxidation
but is resistant to reduction. This property permits the sporopollenin
persistence as an unaltered polymer in sediments of great age, e.g the
Ordovician period, 400 million years ago. Sporopollenin is a mixture of
fatty acids, phenyl-derivatives as p-coumaric acid, and carotenes [1].
Its nanostructure is not yet completed revealed. Therefore, more studies
must be performed. A number of models have been proposed for the
sporopollenin nanostructure of spores and pollen grains [2]. Rowley et
al. [3-4] interpret exine structure as being formed by helical subunits,
based on transmission and scanning electron microscope (TEM and SEM)
studies. The atomic force microscopy (AFM) is the ideal method to study
the sporopollenin nanostructure [5] since the arrangement of components
is not visualized easily through other microscope techniques (e.g. TEM
and SEM). In the present work, we used AFM to study the sporopollenin
nanostructure of the Ilex paraguariensis A.St.Hil. exine, an Angiosperm
(Aquifoliaceae).