Walton Reid and Dr. Klaus Wolf
Fig. 1 Clockwise: plant, leaf, leaf tip (bar = 1mm), chemical-rich glandular outgrowths (bar = 0.1mm)>
THE 'NAKED' human eye is unable to distinguish between objects that are nearer than about one tenth of a millimetre to each other. The smallest single speck that the human eye can see is therefore about one tenth of a millimetre in diameter.
Microscopes are instruments with greater resolving power than the human eye, in that they can be used to view objects that are smaller than one tenth of a millimetre. Additionally, microscopes provide enlarged images of tiny objects and allow the user to see much more detail than is possible with the naked eye.
The term 'microscope' usually refers to the Light or Optical microscope (OM), which uses visible light to illuminate the object being viewed. Visible light allows the viewing of much less detail than does the constituent of matter called electrons. Microscopes which use electrons to 'illuminate' the object being viewed are called electron microscopes, the first of which was constructed in 1931 by German Physicists, notable among whom was Ernst Ruska, who shared the Nobel Prize for Physics in 1986.
Electron microscopes are of two basic types - the scanning electron microscope (SEM), which is used to view surface features of objects and the transmission electron microscope (TEM), which is used to view internal features. Whereas a typical OM can be about 38cm high, 22cm wide and 31cm deep, a typical TEM can be 250 cm high, 200 cm wide and 142 cm deep. Since electron microscopes use electrons and not visible light to impinge on objects, the images produced by electron microscopes are in shades of grey and never in colour. All coloured electron micrographs (as the images are called) are artificially coloured.
Fig. 2 Comparative sizes of TEM and ordinary OM
The Electron Microscopy (EM) Unit at the University of the West Indies (UWI), Mona via its various microscopes has conducted and facilitated research, which requires the observation and study of objects that are completely invisible to the naked eye. This Unit was established in the 1960s. The Coconut Industry Board in Jamaica, having problems with Lethal Yellowing disease in coconut palms, communicated with the United Kingdom who got the Overseas Development Agency (ODA) to furnish the EM Unit with a TEM for Lethal Yellowing research. This TEM was commissioned in 1973.
After years of dedicated Lethal Yellowing research, the TEM was donated by ODA to the UWI for its own use. Since specimens viewed via TEM have to be about one ten thousandth of a millimetre thick, biological material which can be readily thinned and bacteria-sized particles were mainly investigated at the EM Unit, in its early days.
With the acquisition of an SEM in 1982, research at the EM Unit expanded to include non-biological material and larger specimens. In 1995 an advanced OM was acquired and later upgraded with a high resolution digital camera and associated computer accessories. The Unit, through the use of its equipment to see what cannot be conventionally seen, has been able to:
Clarify ambiguities in histological results of children dying from severe oedematus malnutrition;
Identify two types of glandular outgrowths of the local plant Cleome viscosa (Tickweed), which has strong anti-bacterial and nematocidal properties;
Map the structure of stink bug eggs, showing which sections are resistant to chemical attack and which sections are not;
Show that the only proper insect (Belgica antarctica) in Antarctica, uses its eyes both to see and to feel objects in its harsh environment. Image with Purple arrow.
Other researchers were facilitated in their investigation of plant viruses, tissue culture, alumina production from bauxite mining, rollers for grinding sugar cane in factories and preparation of canned foods, to name a few. Collaborative work and exchange programmes with researchers, stretched from Finland, through Mexico to New Zealand.
Each of the few examples cited concerning the use of electron microscopy hints at benefits that Jamaica and the international community can or has reaped from this aspect of research. Electron microscopy in Jamaica is therefore to be encouraged, and maintained. The government of Japan, under a cultural grant has contributed significantly in this respect by replacing the EM Unit's old, damaged TEM with a modern and efficient machine. The 24 year old, ailing SEM is still to be revived or replaced.
LITERATURE
For persons interested in more detailed information on electron microscopy, the following publications are helpful:
Meyer-Rochow, V.B. and Reid, W.A. (1995) Electron Microscopy in Jamaica: Applications and Techniques. W.I. Med. J. 44:44-50.
Bubel, A. and Fitzsimmons, C. (1989) Microstructure and Function of Cells. Ellis Horwood Limited, England.
Bozzola, J.J. and Russell, L.D. (1992)
