592
ILSE LASNITZKI
in motion a complex reaction involving, in particular, the endocrine
glands, and the primary effect of a given hormone may be modified
or masked by the output of other hormones by these organs. This
makes it difficult to unravel the specific effect of a given hormone on
its target organ. Tissue Culture, on the other hand, provides a simple
system, independent of blood and nerve supply, in which the essential
effect of individual hormones and their mechanism of action on cells
and target tissues can be studied under controlled experimental conditions, and the question decided whether or not the hormone acts
on the cellular level. Furthermore, the interaction with other hormones
can be investigated by applying them singly and in combination and
the changes can be detected and followed in detail from an early stage.
Observations on the action of hormones on cells in vitro go back
nearly forty years. In those early days tissue cultures, mainly in the
form of chick-embryo-heart fibroblasts, were used for hormone studies
and the effects were expressed as a decrease or increase of the area of
outgrowth. This, together with the fact that the hormones were not
properly quantitated and often contained impurities, makes it hardly
surprising that the results were often inconsistent or contradictory.
These difficulties have now been largely overcome, and hormonal
effects on cells can now be evaluated quantitatively by cell-counts or
by changes in biochemical pattern. By these means, valuable and
consistent results have been obtained. However, the criterion of effect
is, usually, limited to these two aspects, and it must be remembered that
the majority of hormones have, apart from a possible action on cell
replication, other more specific effects. They may interfere with the
normal differentiation of certain tissues or be indispensable for the
development and specialization of their target organs. This, together
with the fact that cell cultures derived from hormone-sensitive organs
usually lose the hormone-sensitivity of their parent tissue, makes organ
cultures rather than cell cultures the obvious choice for the study of
specific hormone effects.
Recent improvements in techniques have made it possible to cultivate
successfully many more target organs than before, and thus to widen
the scope ofthe investigation; the introduction of "chemically defined"
media by many workers has eliminated sources of errors inherent in
the use of "natural" media which contain small amounts of hormones.
In this chapter the action of insulin, of anterior pituitary and sex
hormones, and the effects of corticosteroids, thyroxin and parathormone
on growth and differentiation of cell and organ cultures will be described.
The action of hormones on particular tissues in vitro is also discussed
in the chapters on the behaviour of the tissues themselves. Readers
ILSE LASNITZKI
in motion a complex reaction involving, in particular, the endocrine
glands, and the primary effect of a given hormone may be modified
or masked by the output of other hormones by these organs. This
makes it difficult to unravel the specific effect of a given hormone on
its target organ. Tissue Culture, on the other hand, provides a simple
system, independent of blood and nerve supply, in which the essential
effect of individual hormones and their mechanism of action on cells
and target tissues can be studied under controlled experimental conditions, and the question decided whether or not the hormone acts
on the cellular level. Furthermore, the interaction with other hormones
can be investigated by applying them singly and in combination and
the changes can be detected and followed in detail from an early stage.
Observations on the action of hormones on cells in vitro go back
nearly forty years. In those early days tissue cultures, mainly in the
form of chick-embryo-heart fibroblasts, were used for hormone studies
and the effects were expressed as a decrease or increase of the area of
outgrowth. This, together with the fact that the hormones were not
properly quantitated and often contained impurities, makes it hardly
surprising that the results were often inconsistent or contradictory.
These difficulties have now been largely overcome, and hormonal
effects on cells can now be evaluated quantitatively by cell-counts or
by changes in biochemical pattern. By these means, valuable and
consistent results have been obtained. However, the criterion of effect
is, usually, limited to these two aspects, and it must be remembered that
the majority of hormones have, apart from a possible action on cell
replication, other more specific effects. They may interfere with the
normal differentiation of certain tissues or be indispensable for the
development and specialization of their target organs. This, together
with the fact that cell cultures derived from hormone-sensitive organs
usually lose the hormone-sensitivity of their parent tissue, makes organ
cultures rather than cell cultures the obvious choice for the study of
specific hormone effects.
Recent improvements in techniques have made it possible to cultivate
successfully many more target organs than before, and thus to widen
the scope ofthe investigation; the introduction of "chemically defined"
media by many workers has eliminated sources of errors inherent in
the use of "natural" media which contain small amounts of hormones.
In this chapter the action of insulin, of anterior pituitary and sex
hormones, and the effects of corticosteroids, thyroxin and parathormone
on growth and differentiation of cell and organ cultures will be described.
The action of hormones on particular tissues in vitro is also discussed
in the chapters on the behaviour of the tissues themselves. Readers