The use of the scanning electron microscope (SEM) to reconstruct the ultrastructure of sporoderm
2017
Zavialova, Natalia | Karasev, Eugeny
Scanning electron microscope (SEM) data can help in the interpretation of transmission electron microscope (TEM) ultrathin sections and reconstruction of the three-dimensional inner structure of large palynological objects like megaspores. For a SEM study of the inner structure of fossil megaspores, we tried three variants of embedding media: a water solution of glycerine and gum arabic, a water solution of sucrose and polyvinylpyrrolidone, and a mixture of epoxy resins. Semithin sections of fossil megaspores were made, the embedding medium was removed from the sections and they were observed under SEM. Epoxy mixture as an embedding medium and Maxwell's solution as a solvent turned out to be the most appropriate for our purposes. The most suitable way of processing is to embed the object, cut it by turns in semithin and ultrathin sections, and study them with SEM and TEM correspondingly. A combination of SEM and TEM data results in a more profound reconstruction of the inner structure of sporoderms. We used as test objects dispersed megaspores of a supposed lycopsid affinity identified as Maexisporites rugulaeferus Karasev et Turnau 2015 and Otynisporites tuberculatus Fuglewicz 1977. The materials studied are from the Lower Triassic and Upper Permian of the Russian Platform.
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