Longitudinal sections (6 mm
thick) were obtained with a rotary microtome,
mounted on glass slides and stained with 0.05%
toluidine blue O (C.I. 52 040) in 0.1 M phosphate
buffer (pH 6.8).. For scanning electron microscopy
(SEM), samples were dehydratet in ketonic series,
critical point dried with CO2, and coated with
gold–palladium (Silveira, 1989).