SERIAL SECTIONS FOR ELECTRON MICROSCOPY
SERIAL SECTIONS FOR ELECTRON MICROSCOPY
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DOI：
10.1126/science.120.3130.1071
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发表时间：
1954-01-01
期刊：
影响因子：
56.9
通讯作者：
ANDERSON, TF
中科院分区：
文献类型：
--
作者：
GAY, H;ANDERSON, TF
New microtomes (1, 2) enable the operator to cut sections for electron microscopy only a few hundred angstroms thick, permitting lateral resolution of the order of 40 A or better. It is difficult to infer from single ultrathin sections, however, the three-dimen-sional structure of the cell or its organelles. To reconstruct unknown cellular structures in three dimen-sions, it seems essential to obtain and examine serial sections. All the microtomes in current use produce ribboins of sections, which float from the knife edge onto thesurface of a liquid in a collecting trough. The problem is to pick up the ribbons and align theIm on the electron-microscope grid so that the ma-terial to be studied is not obstructed by the bars. This report (3) describes methods for picking up ribbons of serial sections with a Formvar-coated wire loop, and then placing them over the slits in Sjostrand-type specimen holders (obtained from Smethurst, High-Light, Ltd., Sideot,-Lanes., Eng-land). By this procedure any desired number of serial sections can be collected routinely and examined in the electron microscope. The electron micrographs in Fig. 1, representing 18 serial sectionsthrough the endoplasmic reticulum of the cytoplasm of a salivarygland cell from the larva of Drosophila melanogaster, were made by this method, which is described here. The tissue is fixed in 1-percent buffered osmium tetroxide and imbedded in n-butyl methacrylate (4). The methaerylate block is trimmed (1) under the dissecting microscope as close as possible to the desired cells, to leave a surface rectangle about 0.3 by 0.08 mm. This block isoriented in the microtome with its long diimiension parallel to the knife edge, and when sectioning is begun a straight ribbon is usually ob-tained.After 15 to 25 sections have been cut, the ribbon has to bedetached from the knife edge. This is facilitated by the use of a trough (Fig. 2) in which the liquid level can be controlled by manipulation of a hypo-dermic syringe connected by a plastic tube toan open-ing in the baseof the trough. The level of the liquid is raised above the knife edge to form a well-rounded meniscus, and the ribbon is detached with a fine hair. The ribbon of sections is then floated from the shallow liquid near the knife edge to a deeper part of the trough. It is removed from the liquid in the following way.
