In 1985 we developed an ultrahigh-resolution scanning electron microscope with a resolution of 0.5 nm. It is equipped with a field emission gun and an objective lens with a very short focal length. In this study we report a survey of some different preparation techniques and biological specimens using the new scanning electron microscope. Intracellular structures such as cell organelles were observed surprisingly sharper than those observed by ordinary scanning electron microscopes. However, at magnifications over 250,000 x, platinum particles could be discerned as scattered pebbles on the surface of all structures in coated materials. Using an uncoated but conductively stained specimen, we successfully observed ribosomes on a rough endoplasmic reticulum at a direct magnification of 1 million. In these images some protrusions were recognized on the ribosomes. Ferritin and immunoglobulin G were used as samples of biological macromolecules. These samples were observed without metal coating and conductive staining. The ferritin particles appeared as rounded bodies without any substructure on the surface and immunoglobulin G as complexes of three-unit bodies. In the latter the central body might correspond to the Fc fragment and two side ones to Fab fragments. We assume that ultrahigh-resolution scanning electron microscopy is an effective means for observation of the cell fine structures and biological macromolecules. It will open a new research field in biomedicine.

A histologically uncommon soft‐tissue tumor of the extremities and neck of a 54‐year old male is reported. The solid, bony‐hard tumors occurred at the inner region of the right thigh at 44 years of age with additional tumor formation at the posterior region of the same thigh, at the inner region of the right upper arm and at the neck during the following 10 years. All tumors were located in the deep muscle layer. The neck tumor directly invaded the fifth cervical vertebra and later the upper mediastinum. Histologically, all three tumors of the extremities contained mixed lobular growths of round to fusiform cells with myxoid matrix and an extensive bone formation. The tumor cells showed a small round nucleus and eosinophilic cytoplasm lacking cytoplasmic glycogen. The myxoid matrix was stained significantly by alcian blue and colloidal iron and was digested completely by pretreatment with hyaluronidase. Another major component was mature bone trabeculae showing a dense meshwork throughout the entire tumor with active bone formation toward the periphery. Positive immunostaining was obtained against anti‐vimentin and S‐100 protein antibodies. We suggest that this uncommon tumor can be tentatively distinguished as an ossifying fibromyxoid tumor of soft parts, (an entity defined by Enzinger et al.), differing from other previously described soft‐tissue tumors. Acta Pathol Jpn 41: 480–486, 1991.

SUMMARY The development of ultrahigh‐resolution scanning electron microscopes (SEMs) has made the observation of biological macromolecules feasible, but adequate preparation methods have not yet been established. Although it has been possible to observe some molecules after they have been spread on a carbon substrate, this method has not proved suitable for other molecules which exhibit lower contrast, or are more susceptible to damage by the electron beam. In this study we have applied heavy‐metal impregnation methods using phosphotungstic acid, uranyl acetate, or osmium tetroxide mordanted by tannic acid. In addition, contamination due to the electron beam was reduced by improving the vacuum in the specimen chamber, and by the use of a heated specimen stage. Using these measures, haemocyanin, ferritin, apoferritin, thyro‐globulin and immunoglobulin M were successfully imaged. Ultrahigh‐resolution SEM seems likely to become an important means for studying the morphology of biological macromolecules.

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Cervical intervertebral discs of ninety-seven patients with cervical disorders were studied with magnetic resonance imaging (MRI), to examine ageing changes of the discs and the relation between their changes and clinical signs. The MRI of cervical intervertebral discs was classified into four types and twelve subtypes. Disc degeneration began to appear in the second decades and became severe after the fourth decades. The degenerated discs increased with ageing. Cervical intervertebral disc herniation was mostly seen at the C5-C6 level. As the clinical signs became severe, discs of type IIIb increased, and incursions on the cervical cord at the involved level became evident.