108
C H A R I T Y W A Y M O U T H
given cell has a precise qualitative requirement for a single amino acid
(or other metabolite), unless this requirement is related to the specific
background of the rest of the environment, physical and chemical.
The acceptance of the idea that every cell type may be expected to
have individual requirements has been slow, but it is encouraging to
read in a recent review of the composition of physiological saline
solutions (Lockwood, 1961) that, even at the ionic level, "the ionic
requirements of cells should not necessarily be regarded as being
similar to the concentrations present in the bulk of a satisfactory saline"
and that "a single physiological saline is unlikely to provide optimum
conditions for all the tissues of an animal, and the ionic composition
must be adjusted according to the tissue and the tissue function under
study". This principle is of more general application, beyond the inorganic components. It is to be expected that the nutritional needs of
tissues will reflect their individualities and "with our present knowledge
of metabolism it is obvious that there will never be a universal medium
for all cell-types" (Paul, 1960). Examples to support this view are
multiplying, and some will be found below.
Lockwood (1961) also points to one of the weaknesses of the imitative
method of designing physiological solutions. The surface charge upon
biological membranes affects the ionic concentrations in the cell
surface and "polyvalent proteins present in blood may be expected
to modify the charge, and hence the ion concentration, at the cellmembrane interface. Solutions lacking proteins may thus have to have
ion concentrations differing from those in blood if the concentrations
at the interface are to be maintained at the appropriate level". Among
many properties of cells which have to be taken into consideration
in designing media to fit their needs is that of the developmental age
of the donor animal. The same author (Lockwood, 1961) points out
that the body fluids of vertebrate embryos are consistently more dilute
than those of the corresponding adult, suggesting that a lower ionic
concentration should be applied to foetal cells. Quite wide variations
in NaCl concentration (the principal salt in all media) can be tolerated
by many cells (Carrel and Burrows, 1911; Willmer, 1927; Brues and
Masters, 1936; Schrek, 1944; Stubblefield and Mueller, 1960). That
a total ionic concentration near that of blood is not necessarily best for
all cells is exemplified by the recent finding of Trowell (1962) that rat
lymph-nodes, under his conditions of culture, thrive on a much lower
NaCl concentration (0-4%) than other mammalian organs.
White (1946, 1949) from experience of success in growing plant
tissues in completely defined solutions, was among the first to design
synthetic solutions intended to fulfil the complete nutritional needs
of explanted animal cells. His solutions were built mainly on the imita-
C H A R I T Y W A Y M O U T H
given cell has a precise qualitative requirement for a single amino acid
(or other metabolite), unless this requirement is related to the specific
background of the rest of the environment, physical and chemical.
The acceptance of the idea that every cell type may be expected to
have individual requirements has been slow, but it is encouraging to
read in a recent review of the composition of physiological saline
solutions (Lockwood, 1961) that, even at the ionic level, "the ionic
requirements of cells should not necessarily be regarded as being
similar to the concentrations present in the bulk of a satisfactory saline"
and that "a single physiological saline is unlikely to provide optimum
conditions for all the tissues of an animal, and the ionic composition
must be adjusted according to the tissue and the tissue function under
study". This principle is of more general application, beyond the inorganic components. It is to be expected that the nutritional needs of
tissues will reflect their individualities and "with our present knowledge
of metabolism it is obvious that there will never be a universal medium
for all cell-types" (Paul, 1960). Examples to support this view are
multiplying, and some will be found below.
Lockwood (1961) also points to one of the weaknesses of the imitative
method of designing physiological solutions. The surface charge upon
biological membranes affects the ionic concentrations in the cell
surface and "polyvalent proteins present in blood may be expected
to modify the charge, and hence the ion concentration, at the cellmembrane interface. Solutions lacking proteins may thus have to have
ion concentrations differing from those in blood if the concentrations
at the interface are to be maintained at the appropriate level". Among
many properties of cells which have to be taken into consideration
in designing media to fit their needs is that of the developmental age
of the donor animal. The same author (Lockwood, 1961) points out
that the body fluids of vertebrate embryos are consistently more dilute
than those of the corresponding adult, suggesting that a lower ionic
concentration should be applied to foetal cells. Quite wide variations
in NaCl concentration (the principal salt in all media) can be tolerated
by many cells (Carrel and Burrows, 1911; Willmer, 1927; Brues and
Masters, 1936; Schrek, 1944; Stubblefield and Mueller, 1960). That
a total ionic concentration near that of blood is not necessarily best for
all cells is exemplified by the recent finding of Trowell (1962) that rat
lymph-nodes, under his conditions of culture, thrive on a much lower
NaCl concentration (0-4%) than other mammalian organs.
White (1946, 1949) from experience of success in growing plant
tissues in completely defined solutions, was among the first to design
synthetic solutions intended to fulfil the complete nutritional needs
of explanted animal cells. His solutions were built mainly on the imita-