The artificial cell design

Current interest in high voltage electron microscopy, especially in the scanning mode, has prompted the development of a method for determining the contrast and resolution of images of specimens in controlled-atmosphere stages or open to the air, hydrated biological specimens being a good example. Such a method would be of use in the prediction of microscope performance and in the subsequent optimization of environmental cell design for given circumstances of accelerating voltage, cell gas pressure and constitution, and desired resolution.Fig. 1 depicts the alfresco cell of a focussed scanning transmission microscope with a layer of gas L (and possibly a thin window W) between the objective O and specimen T. Using the principle of reciprocity, it may be considered optically equivalent to a conventional transmission electron microscope, if the beams were reversed. The layer of gas or solid material after the specimen in the STEM or before the specimen in TEM has no great effect on resolution or contrast and so is ignored here.

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Osmolarity and Artificial Cell Damage in Ischemic Myocardium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158868 ◽

1990 ◽

Vol 48 (3) ◽

pp. 262-263

Author(s):

Richard Montione ◽

Muhammad Ashraf

Keyword(s):

Cell Damage ◽

Uranyl Acetate ◽

Tissue Preservation ◽

Rat Myocardium ◽

En Bloc ◽

Cellular Changes ◽

Artificial Cell ◽

Cacodylate Buffer ◽

Isotonic Buffer ◽

Perfusion Fixation

Osmolarity of a fixative vehicle has long been known to have an effect on the tissue preservation. An increase in tissue osmolarity occurs in ischemia-damaged tissue and affects the morphology. In this study, we examined cellular changes in ischemic rat myocardium induced by varying fixative toxicity.Rats were sacrificed by decapitation and the hearts immediately removed and retrogradily perfused through the aorta with anoxic Kurbs-Henseleit medium. Hearts were then placed in a bag with a small amount of medium at 37°C for 90 minutes. Hearts were perfusion-fixed using 2% glutaraldehyde in 0.1 M cacodylate buffer pH -7.3 at three osmolarities. The isotonic buffer was adjusted to 311 mOsm/kg using D-manitol. Hypertonic buffers were adjusted to 375 and 400 mOsm/kg. One-half hour after perfusion fixation, the hearts were sliced and cut into small blocks and allowed to fix overnight at 4°C. Blocks were post fixed in osmium, en bloc stained in uranyl acetate, dehydrated in ethanol and embedded in Spurr medium.

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