20
A . M O S C O N A , O . A . T R O W E L L A N D E . N . W l L L M E R
explanted, and, according to the size selected, the conditions for their
culture must be varied. In general terms, cells may be cultured as
isolated and independent units (cell culture); small pieces of tissue may
be cultured under conditions which favour the growth and migration
of their cells and under which they tend to become modified to a greater
or less extent into cell colonies (tissue culture), or thirdly, pieces of tissue,
or whole organs if they are small enough, may be cultured in such a
way as to preserve their general organization and to allow the continuation of, or development of, their normal functions (organ culture).
Each type of culture has its own advantages and disadvantages and
poses its own problems of technique. It will be advantageous, therefore,
to review some of the main methods which are commonly employed
and to indicate their scope, merits and limitations. It is of the utmost
importance that the interpretation of all findings in Tissue Culture,
using the term in its broadest sense, should be made with strict reference
to the method employed, since the behaviour of cells is always intimately
dependent on their immediate environment both physical and chemical,
and the life of a cell cannot be separated from the conditions under
which it lives.
Since excellent monographs already exist (Fischer, 1930; Cameron,
1950; Parker, 1958; Paul, 1959; White, 1961; Penso and Balducci,
1963) which describe the main methods available, and other special
methods are discussed in their appropriate contexts in the following
chapters, the purpose of this chapter, except in the cases of organ
culture and the making of cell suspensions where some important
advances of general interest have recently been made, is not so much
to provide practical details of the various methods as to try to make
some assessment of their relative merits and demerits, of their useful
applications and of the biological effects which they may have on the
cells or tissues under investigation.
In discussing the various methods it will be convenient to interpret
the word "culture" to mean that the cells or tissues can be kept for a
minimum of approximately 24 h at their normal temperature and that
throughout this time they remain alive, reasonably active and relatively
normal in appearance, though the term "normal" has sometimes to
be given a rather wide meaning. It is obvious that no hard and fast
rules can be laid down for distinguishing between survival, maintenance, differentiation and growth. It is equally difficult to draw the
line between ordinary physiological or biochemical experiments on
tissues surviving for a few hours, e.g. investigations on surviving strips
of intestine in baths of physiological salt solution, or measurements of
the metabolism of tissue slices, and similar experiments performed on
"genuine" tissue or cell cultures. Moreover, the differentiation which
A . M O S C O N A , O . A . T R O W E L L A N D E . N . W l L L M E R
explanted, and, according to the size selected, the conditions for their
culture must be varied. In general terms, cells may be cultured as
isolated and independent units (cell culture); small pieces of tissue may
be cultured under conditions which favour the growth and migration
of their cells and under which they tend to become modified to a greater
or less extent into cell colonies (tissue culture), or thirdly, pieces of tissue,
or whole organs if they are small enough, may be cultured in such a
way as to preserve their general organization and to allow the continuation of, or development of, their normal functions (organ culture).
Each type of culture has its own advantages and disadvantages and
poses its own problems of technique. It will be advantageous, therefore,
to review some of the main methods which are commonly employed
and to indicate their scope, merits and limitations. It is of the utmost
importance that the interpretation of all findings in Tissue Culture,
using the term in its broadest sense, should be made with strict reference
to the method employed, since the behaviour of cells is always intimately
dependent on their immediate environment both physical and chemical,
and the life of a cell cannot be separated from the conditions under
which it lives.
Since excellent monographs already exist (Fischer, 1930; Cameron,
1950; Parker, 1958; Paul, 1959; White, 1961; Penso and Balducci,
1963) which describe the main methods available, and other special
methods are discussed in their appropriate contexts in the following
chapters, the purpose of this chapter, except in the cases of organ
culture and the making of cell suspensions where some important
advances of general interest have recently been made, is not so much
to provide practical details of the various methods as to try to make
some assessment of their relative merits and demerits, of their useful
applications and of the biological effects which they may have on the
cells or tissues under investigation.
In discussing the various methods it will be convenient to interpret
the word "culture" to mean that the cells or tissues can be kept for a
minimum of approximately 24 h at their normal temperature and that
throughout this time they remain alive, reasonably active and relatively
normal in appearance, though the term "normal" has sometimes to
be given a rather wide meaning. It is obvious that no hard and fast
rules can be laid down for distinguishing between survival, maintenance, differentiation and growth. It is equally difficult to draw the
line between ordinary physiological or biochemical experiments on
tissues surviving for a few hours, e.g. investigations on surviving strips
of intestine in baths of physiological salt solution, or measurements of
the metabolism of tissue slices, and similar experiments performed on
"genuine" tissue or cell cultures. Moreover, the differentiation which