450
S.A.
MEDICAL
to be viewed sufficiently and extraordinarily thin. Casting
(<the impr.ession of the cell urface on plastic film) and
shadowing (vaporized gold projected on the contours as
a coating) are techniques that have been used for some
time, but they show nothing of the interior of the cell.
For this purpose new methods of sectioning have been
devised which allow preparations with a thickness of
approximately 0·05 micron to be made - a white cell of
about 20 micra in diameter can therefore be cut into 400
sections.
Animal and vegetable cells all contain, with few exceptions, a nucleus, mitochondria, cytoplasm, Golgi bodies,
and centrioles, which are visible under the optical microscope. These organelles can be sedirnented by high-speed
centrifugation without necessarily disturbing cell function,
but since 1940 a method of differential ultra-centrifugation
of crushed cells has enabled biochemists to obtain fractions
containing in a pure state the nuclei, mitochondria,
secretory granules, microsomes, and other organelles, for
study of their enzymes and functions. All this is very
exciting, but it must be borne in mind that such studies,
valuable and important as they are, are made in an artificial environment.
With magnifications up to 200,000 diameters, the internal
structure of cells can be clearly observed with the electron
microscope, and it may be possible on occasion to see
molecules in their positions in the intact cell; cellular
organization may It!hus Ibe considered in <terms of molecular
structure (molecular ecology).
A network of canaliculi and more or less flattened
vacuoles is present in the cytoplasm of practically all cells;
this endoplasmic reticulum varies greatly in different cells,
and its arrangement also varies from one moment to
another within the same cell. Some of the vacuoles con-
9 June 1962
JOURNAL
tain the Palade granules. These structures have important
functions, for example, the role of the granules in protein
synthesis, and the passage of substances along the network
of the reticulum into and out of the cell.
The mitochondria are granu!ations that were discovered
quite a long time ago, but only recently, with the technique
of differential centrifugation, has their isolation and
chemical analysis become possible; and one of the most
important discoveries made in recent years is the fact
that it is in the mitochondria that the process of oxidation
in the cell takes place. The electron microscope has revealed structures resembling crests or lamellae in the
mitochondria, and many laboratories are engaged in discovering where along these crests the various enzymes of
the Krebs cycle are placed, and what are the other
functions of the mitochondria.
The centrioles are curious bodies, cylindrical in structure,
with sides made up of nine small tubes. They play an
important part in mitosis. Surrounding the centriole in most
cells is the strange formation known as the Golgi body or
apparatus which comprises a number of structures known
as dicytosomes. Their function remains to be established.
The electron microscope has also revealed that the cell
surface is not smooth and regular, but covered with projections and depressions of varying depths.
Enough has been stated here to indicate some of the
remarkable observations that have been made in recent
years with regard to the ultrastructure of cells. 0 mention
has been made of the nucleus and its structure about which
much remains to be learned. In fact, there is tremendous
scope for research in unravelling the detailed structure and
function of the different types of cells despite the vast
accumulation of facts already known.
1. Bessis, M. (1960): The Ultrastructure af Cel/s. Basle:
graphs.
Sandoz Mono-
WORLD LIST OF FUTURE INTERNATIONAL MEETINGS
Following is a list of international medical meetings to be
held during the period January-June 1963. Alterations and
additions to this list will continue to be published in the
Journal from time to time, together with information concerning meetings taking place before January 1963. For the
full list of meetings taking place between July-December 1962,
see the issue of the Journal for 13 January 1962 (36, 38).
Seventh International Congress on Diseases of the Chest.
ew Delhi, 20 - 24 February 1963. Murray Komfield, American College of Chest Physicians, 112E Chestnut St., Crncago 2,
T
1lI.
Congress, Ecuador,
ew York 22, Y.
International Anaesthesia Research Society 37th Congress,
San Francisco, 17 - 21 March 1963. Dr. A. William Friend,
227 Wade Park Manor, Cleveland 5, Ohio.
International Association for Dental Research, 41st General
Meeting, Pittsburgh, March 1963. Dr. 1. Muhler, 1120 W.
Michigan St., lndianapolis 2, Ind.
Pan
American
Medical
Association
February 1963. 745 Fifth Avenue,
T
First World Congress for the Early Detection and Prevention
of Diabetes, Chicago, 7 - 10 April 1963. Dr. B. R. Hearst,
55 E Washington St., Suite 1642, Chicago 2, Ill.
ALTERATIONS A D ADDITIONS
Society for General Microbiology, 35th General Meeting,
Reading, Eng., 27 - 29 September 1962. clo Institute of
Biology, 41 Queen's Gate, London, S.W.7. (Meeting jointly
with etherlands Society for Microbiology.)
Latin-American Society of Plastic Surgery, 1st Regional
Central American Congress, 26 - 31 August 1962. Secretary
General, clo Sociedad Colombiana de Cirurgfa Plastica y
International Meeting in Forensic Immunology, Medicine,
Pathology and Toxicology, London, 16 - 24 April 1963.
Secretariat, 28 Portland Place, London, W.l.
Second
Asia and
Oceania
Congress
of Endocrinology,
Sydney, 28 May - '2 June 1963. P. 1. Claringbold, University
of Sydney, Sydney, N.S.W., Australia.
International Organization against Trachoma, Paris, May
1963. Dr. J. Sedan, Ligue International Contre le Trahcome,
94 rue Sylvabelle, Marseilles, France. (During 70th Congress
of French Society of Ophthalmology.)
Pan American Diabetic Congress, Crncago, May 1%3. Congress Committee, Dr. B. R. Hearst, 55 E. Washington St.,
Suite 1646, Chicago, 2, Ill.
International Society for Rehabilitation of the Disabled, 9th
World Congress, Copenhagen, 23 - 28 June 1963. 701 First
Avenue, ew York, NY.
World Commission on Cerebral Palsy, Copenhagen, 23 - 28
June 1963. P. Hq,eg Albrethsen, Samfundet for Vanf.pre,
Esplanaden 34, Copenhagen K, Denmark.
OTlFIED DURING MAY 1962
Reparadora, Hospital Militar Central, Bogota, Colombia.
European Society of Cardiovascular Surgery, Stockholm,
1 - 4 July 1962. Prof. G. Arnuff, 1 PI. Gailleton, Lyons.
France.
International Commission for
Prevention of Alcoholism,
SeattIe, 6 - 17 August, 1962. 6830 Laurel St.
12, D.e.
.W., Washington
-