Hard-Copy Imaging Options

Photographic film has played a central role in the recording of microscope images since the invention of photography in the 1830s. Photography rapidly creates an accurate record of the microscopic specimen and avoids the subjectivity that was inherent in written and artistic descriptions of visual observations. Both instant and conventional films offer high resolution, the ability to record a large tonal gradation, and a stable media for long-term data storage.Newer techniques, such as thermal, ink jet, and laser prints, have grown in popularity because they offer ease-of-use or lower per-image cost. Despite recent improvements, none of these techniques offer the resolution or stability of a photograph. In general, people have been forced to sacrifice quality and permanence in order to achieve the lower per-image cost and ease-of-use promised by alternative recording systems.

High-performance transmission electron microscopy of cryospecimens

Chemical fixation, resin embedding and subsequent staining with heavy metals can both produce artefacts and limit the resolution in the electron microscopic specimen /1-5/. The objective is thus to observe the specimens in the electron microscope in the frozen-hydrated state, the one most similar to the native state.All preparation steps such as cryofixation, cryosectioning and cryotransfer to the cryo-transmission electron microscope (CryoTEM) should be performed below 145K /5/ in order to observe the specimen in a matrix of vitrified ice avoiding any crystallization artefacts. In the CryoTEM itself the temperature of the frozen-hydrated specimen should be kept much lower to avoid devitrification caused by the electron beam /1/. - To meet all these requirements a special cryotransfer system and cryostage for the Zeiss transmission electron microscopes have been developed /7/.

A STUDY OF MASS LOSS AND PRODUCT FORMATION AFTER IRRADIATION OF SOME DRY AMINO ACIDS, PEPTIDES, POLYPEPTIDES AND PROTEINS WITH AN ELECTRON BEAM OF LOW CURRENT DENSITY

Amino acids, peptides, polypeptides and proteins were irradiated with electrons at 70-kv accelerating potential in an electron microscope mockup. Loss of mass and chemical changes occur almost instantaneously. For a given dose rate an organic object is converted to a steady state product. This is characterized by a poorly structured infrared pattern, unchanging elemental composition. The higher the polymerization of the target the smaller was the effect of the irradiation. Such studies conducted outside of the electron microscope reveal only qualitatively what might occur to the electron microscopic specimen during observation.

Hyperkeratosis of the epithelium of the lacunae of the pharyngeal tonsil affected by Leptotrix

Rhino-laryngo-otiatric section30th meeting 14 March 1930Dr. BN Lebedevsky demonstrated on a microscopic specimen hyperkeratosis of the epithelium of the lacunae of the pharyngeal tonsil, affected by Leptotrix.