At the heading stage, the fresh first internode and leaf sheath
from the mutant and its wild type were cut into thin pieces and
segments respectively and then fixed in the fixative solution (75%
ethanol, 5% acetic acid, 5% glycerol and 5% formaldehyde) for at
least one day. The leaf sheath samples were dehydrated through a
graded ethanol, transparented in xylene over night, washed with
ethanol and observed under a light microscope. For scanning electron
microscopy, the fixed thin pieces of internode were critical
point dried, sputter-coated with gold and observed with a scanning
electron microscope (UANTA 200).