THE MEASUREMENT OF MASS, THICKNESS, AND DENSITY IN THE ELECTRON MICROSCOPE
Open Access
- 1 September 1960
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 8 (1), 1-11
- https://doi.org/10.1083/jcb.8.1.1
Abstract
A description is given of quantitative methods using the electron microscope which can be applied to specimens with much smaller dimensions than those which can be used with the established cyto-chemical methods based on the use of the interference microscope and the techniques of ultraviolet and X-ray absorption. A discussion of electron scattering shows that under chosen operating conditions in the electron microscope the effective total mass-scattering coefficient S of a specimen is almost independent of its chemical composition. An order-of-magnitude agreement is observed at four accelerating voltages between experimental total scattering cross-sections for polystyrene and theoretical values for carbon. The contrast in a micrograph taken under standardised conditions is interpreted in terms of differences in specimen mass-thickness. The measurement of mass, thickness, and density of discrete particles and thin sections in the absence of sublimation is discussed in terms of relevant object models on the assumption of a constant, experimentally determined, value of S. The validity of the proposed methods was examined by measuring the masses of the heads of ram spermatozoa (about 7 x 10-2 gm) and T2 bacterio-phage (about 3 x 10-16 gm) in the electron microscope. The values agreed reasonably well with those found by interference microscopy and sedimentation-diffusion measurements, respectively. Errors in S and magnification due to contamination and their effects on the results are considered in detail. An application of the methods to a typical electron microscope specimen was demonstrated by measuring the mass of heads of the T2 bacteriophage after staining with uranyl acetate. Errors of measurement are discussed and a minimal measurable mass estimated. Further applications of quantitative electron microscopy are proposed.Keywords
This publication has 14 references indexed in Scilit:
- The Possibility of distinguishing between Substances shown on Electron MicrographsNature, 1959
- QUANTITATIVE KONTRASTIERUNGS-VERSUCHE FUR DIE ELEKTRONENMIKROSKOPIE .2. DIE KONTRASTIERUNG DES TABAKMOSAIKVIRUS NACH EINER FORMALDEHYDFIXATION UND MIT EINER CAESIUM, BARIUM, WISMUT UND MANGANVERBINDUNG1959
- Determination of the Mass Thickness of Cell Membranes from their Electron MicrographsNature, 1958
- II.—A SYMPOSIUM ON ELECTRON STAININGJournal of the Royal Microscopical Society, 1958
- [Method for electron microscopic mass density measurement of non-crystalline objects].1955
- Quantitative cytochemical methods for the study of cell metabolismCellular and Molecular Life Sciences, 1955
- ELECTRON DENSITOMETRY OF STAINED VIRUS PARTICLESThe Journal of cell biology, 1955
- A high speed recording microdensitometer suitable for cytological researchExperimental Cell Research, 1955
- A compact console-type electron microscopeJournal of Scientific Instruments, 1954
- MORPHOLOGY OF THE SEVEN T-BACTERIOPHAGESJournal of Bacteriology, 1953