Acoustic microscopy: resolution of subcellular detail.

Abstract

Recent advances now permit the use of scanning acoustic microscopy for the analysis of subcellular components. By sequential viewing of identified fixed cells with acoustic, light, and electron microscopy, we have established that the acoustic microscope can readily detect such features as nuclei and nucleoli, mitochondria, and actin cables. Under optimal conditions, images can even be obtained of filopodia, slender projections of the cell surface that are approximately 0.1-0.2 Jim in diameter. Small objects separated by as little as 0.5-0.7 jum can successfully be resolved. Three aspects of the acoustic micrographs prepared in this preliminary survey seem especially prominent. These are, first, the extraordinary level of acoustic contrast that can differentiate the various cytoplasmic organelles, even in regions of very thin cytoplasm; second, the reversals in acoustic contrast that occur when altering the plane of focus; and third, the sensitivity of the acoustic response to overall cytoplasmic thickness. The acoustic microscope uses a novel source of contrast that is based on local mechanical properties. In addition, it can provide a degree of resolution that is comparable to that of the light microscope.Much of our current understanding of cellular structure and function has been gained through the application of a variety of microscopic techniques. With light microscopy, advances in the methods of fixation and staining [for example, the recent development of immunofluorescence microscopy (see ref.1)] and in optical systems [for example, phase contrast (2), Nomarski (3), Hoffman modulation (4), and polarized light microscopy (5)] have permitted major increases in knowledge about both living and fixed biological material. The electron microscope, in both the transmission and scanning modes, has of course greatly extended our understanding of the fine structure of nonliving preparations.We now report the application of a novel type of microscopy, acoustic microscopy, to the analysis of subcellular components. We compare images obtained in the acoustic microscope with images of the same cells obtained by light and electron microscopy. This report is an update of an earlier paper (6), in which the visualization of single cells with the scanning acoustic microscope was first described. Since then, advances in acoustic technology have permitted major increases in resolution to a level now comparable to that of light microscopy (7). The impetus toward development of the acoustic microscope rests on the unique method of analysis, the use of high-frequency sound waves. The properties detected by acoustic radiation are different from those detected by either light or electron radiation, and present exciting possibilities for the examination, in a fundamentally new way, of biological material. THE ACOUSTIC MICROSCOPEThe scanning acoustic microscope used in this study was introduced in 1974 by Lemons and Quate (8). The basic functioning of the device as used in the reflection mode can be understood with the aid ...

In vitro characterization of a novel, tissue-targeted ultrasonic contrast system with acoustic microscopy

“…Over the last 25 years, acoustic microscopy has been used to visualize tissues, 12,13 cells, 14 and subcellular organelles 15,16 and to characterize their material [17][18][19] and acoustic properties. 20,21 Our laboratory has utilized acoustic microscopy to quantify atherosclerotic plaque composition, 22 to define ventricular architectural remodeling in cardiomyopathies, [23][24][25] and to physically characterize the disorganization and composition of aortic tissue in Marfan's syndrome.…”

Systematic approach to study of thinly and thickly sectioned melanoma tissues with scanning acoustic microscopy

“…Since the staining and/or fixation of the specimen are not required for the SAM, living cells may be observed directly with the SAM. Furthermore, the SAM can nondestructively image not only the surface but also the internal structure of the specimen with sub-micron resolution [2]. The SAM also has the capability of measuring the mechanical properties (e.g., loss factor and modulus) of tissues.…”

Acoustic microstructure of mature soya bean (Maple Arrow)

“…Acoustic microscopes are used to explore and visualize the microdistribution of viscoelastic properties of solid samples (Lemons & Quate, 1974;Kessler & Yukas, 1978;Hildebrand & Rugar, 1984). Depending on their frequency, ultrasonic (US) waves are capable of penetrating both liquids and solids to a considerable depth, without destroying the specimen, so that acoustic microscopy (AM) is a convenient tool to explore interior planes of thick specimens (Hafsteinsson & Rizvi, 1984;Neild et al, 1985;Daft et al, 1986) or tissue cultures (Johnston et al, 1979;Israel et al, 1980;Hildebrand et al, 1981).…”