1. I N T R O D U C T I O N
1 3
It may then be removed. In the body, also, the reacting cell may be in
a particular reactive state or not, according to other local conditions.
If it is in the reactive state, it may respond characteristically to different
concentrations, and other circulating substances may affect the sensitivity and response of the reacting cell. A hormone liberated by one
gland may act on an apparent "target" organ only indirectly through
another gland or organ, and it may remain inactive without the
intervention of the latter. In a Tissue Culture it is much more likely
that any action which a hormone exerts is a direct one, but, on the
other hand, the reacting cell may be in an abnormal state and problems
of dosage are extremely difficult. Inactivation, adsorption, utilization
and breakdown in other parts of the culture system are all unknown
and unpredictable variables, as they often are in the body. Sometimes
higher doses may be tolerated in vitro than in vivo, sometimes the reverse.
Proflavine is extremely toxic to cells in vitro, but almost harmless on the
surface of the brain (Jacoby, Medawar and Willmer, 1941). The
maintenance of a constant but low concentration of an experimental
agent may be exceedingly difficult in vitro. In stationary cultures the
concentration of the experimental agent in the immediate vicinity of
the cells may fall almost to zero because of rapid utilization or inactivation. Perfusion methods are not yet very satisfactory, probably because
of the accidental removal of other essential metabolites from tissues at a
faster rate than they can be replaced. In many other ways, too, perfusion affects the normal activities of cells.
The chapters which follow will, it is believed, allow the reader to
form some opinion on the contributions which advances in Tissue
Culture have made and are making to the study of the cell and to the
biology of tissues and organs, and will give some idea of the advances
which are likely to accrue from the more recently developed techniques
when these are applied to different tissues and problems.
The guiding principle in the compilation of the book has been that
the study of living cells and tissues is fundamental to biology. Nevertheless, it must be borne in mind that all methods of experimenting upon
living cells inevitably evoke responses from those cells, which are to a
greater or less extent abnormal. Every cell, removed from the body,
either in isolation or as part of a tissue or organ, is inevitably altered,
and it is the business of the biologist and physiologist to assess the value
of all observations in terms of their contribution to the understanding
of normal biological processes. The chapters in this book present the
information on various tissues and systems which has been obtained by
Tissue Culture and has seemed to the various authors to be of significance to the understanding of the normal working of the cells or tissues
in question, or to the understanding of cellular behaviour in general. It
1 3
It may then be removed. In the body, also, the reacting cell may be in
a particular reactive state or not, according to other local conditions.
If it is in the reactive state, it may respond characteristically to different
concentrations, and other circulating substances may affect the sensitivity and response of the reacting cell. A hormone liberated by one
gland may act on an apparent "target" organ only indirectly through
another gland or organ, and it may remain inactive without the
intervention of the latter. In a Tissue Culture it is much more likely
that any action which a hormone exerts is a direct one, but, on the
other hand, the reacting cell may be in an abnormal state and problems
of dosage are extremely difficult. Inactivation, adsorption, utilization
and breakdown in other parts of the culture system are all unknown
and unpredictable variables, as they often are in the body. Sometimes
higher doses may be tolerated in vitro than in vivo, sometimes the reverse.
Proflavine is extremely toxic to cells in vitro, but almost harmless on the
surface of the brain (Jacoby, Medawar and Willmer, 1941). The
maintenance of a constant but low concentration of an experimental
agent may be exceedingly difficult in vitro. In stationary cultures the
concentration of the experimental agent in the immediate vicinity of
the cells may fall almost to zero because of rapid utilization or inactivation. Perfusion methods are not yet very satisfactory, probably because
of the accidental removal of other essential metabolites from tissues at a
faster rate than they can be replaced. In many other ways, too, perfusion affects the normal activities of cells.
The chapters which follow will, it is believed, allow the reader to
form some opinion on the contributions which advances in Tissue
Culture have made and are making to the study of the cell and to the
biology of tissues and organs, and will give some idea of the advances
which are likely to accrue from the more recently developed techniques
when these are applied to different tissues and problems.
The guiding principle in the compilation of the book has been that
the study of living cells and tissues is fundamental to biology. Nevertheless, it must be borne in mind that all methods of experimenting upon
living cells inevitably evoke responses from those cells, which are to a
greater or less extent abnormal. Every cell, removed from the body,
either in isolation or as part of a tissue or organ, is inevitably altered,
and it is the business of the biologist and physiologist to assess the value
of all observations in terms of their contribution to the understanding
of normal biological processes. The chapters in this book present the
information on various tissues and systems which has been obtained by
Tissue Culture and has seemed to the various authors to be of significance to the understanding of the normal working of the cells or tissues
in question, or to the understanding of cellular behaviour in general. It