C H A P T E R 1
Introduction
E. N. W l L L M E R
Physiological Laboratory, University of Cambridge, England
The advantages, from an experimental point of view, of being able
to observe cells and tissues in isolation and away from the controlling
and modifying influences of other tissues in the body are clearly so
great that it is at first sight surprising to find that Tissue Culture of
animal cells and tissues was not attempted seriously until the very end
of the nineteenth century, and really only launched successfully in 1907.
In this respect there is a wide difference between animal tissues and the
tissues of higher plants, for the latter are, on the whole, much more
viable in isolation and the propagation of whole plants from isolated
fragments, has of course, been carried out for centuries.
Tissue Culture, as it is practised today, can be profitably considered
under three headings. There is first of all "tissue culture" proper, in
which small fragments of tissue are explanted into a suitable medium
and encouraged to grow in isolation, to form colonies, and perhaps to
continue some of their normal functions. In such cultures, the original
organization of the tissues may be lost, but the constituent cells emerge
into the zone of outgrowth where their activities may be directly
observed. Secondly there is "cell culture" in which the cells of a tissue,
or even individual cells, are made to grow in much the same way as
bacteria are grown: all the organization of the original tissues in such
cultures is discarded as irrelevant and cell multiplication and growth
in uniform populations are the dominant interests. The cells of different
tissues tend to become "dedifferentiated" and relatively alike in
appearance. Thirdly, in "organ culture", growth is only of minor
interest, but embryological development and the maintenance of
normal physiological functions are the chief aim and object. The outward growth and migration of "dedifferentiated" cells is positively
suppressed and the maintenance of the normal organization of the
tissue is of first importance.
8
Introduction
E. N. W l L L M E R
Physiological Laboratory, University of Cambridge, England
The advantages, from an experimental point of view, of being able
to observe cells and tissues in isolation and away from the controlling
and modifying influences of other tissues in the body are clearly so
great that it is at first sight surprising to find that Tissue Culture of
animal cells and tissues was not attempted seriously until the very end
of the nineteenth century, and really only launched successfully in 1907.
In this respect there is a wide difference between animal tissues and the
tissues of higher plants, for the latter are, on the whole, much more
viable in isolation and the propagation of whole plants from isolated
fragments, has of course, been carried out for centuries.
Tissue Culture, as it is practised today, can be profitably considered
under three headings. There is first of all "tissue culture" proper, in
which small fragments of tissue are explanted into a suitable medium
and encouraged to grow in isolation, to form colonies, and perhaps to
continue some of their normal functions. In such cultures, the original
organization of the tissues may be lost, but the constituent cells emerge
into the zone of outgrowth where their activities may be directly
observed. Secondly there is "cell culture" in which the cells of a tissue,
or even individual cells, are made to grow in much the same way as
bacteria are grown: all the organization of the original tissues in such
cultures is discarded as irrelevant and cell multiplication and growth
in uniform populations are the dominant interests. The cells of different
tissues tend to become "dedifferentiated" and relatively alike in
appearance. Thirdly, in "organ culture", growth is only of minor
interest, but embryological development and the maintenance of
normal physiological functions are the chief aim and object. The outward growth and migration of "dedifferentiated" cells is positively
suppressed and the maintenance of the normal organization of the
tissue is of first importance.
8