110
C H A R I T Y W A Y M O U T H
The series of chemically defined media ( N C T C 107-117) designed
by Evans and Earle and their collaborators (Evans, Bryant, McQuilkin,
Fioramonti, Sanford, Westfall and Earle, 1956a,b; Evans, Fioramonti,
Sanford, Earle and Westfall, 1958; Earle, 1962) were based on analyses
of the amino-acid, amide and amine contents of serum and embryo
extract ultrafiltrates, and were to this extent imitative. "Practically all
commercially available vitamins were used in this medium" (Evans et
al., 1956a), on the comprehensive principle. These media have also
been very widely used (cf. Earle, 1962).
The synthetic media of Eagle (1955a,c,d, 1959) are "minimum
essential" or "basal" media, not complete media, and usually require
to be supplemented with small amounts of serum or serum ultrafiltrate.
However, cells from strain-L, clone 929, have been cultivated in a
modification of Eagle's basal medium in which the amino acids,
glutamine and eight vitamins are supplied at double the specified
concentrations (Merchant and Hellman, 1962).
The efforts of many individuals have contributed to the media
currently in use, and the flow and interchange of ideas between
laboratories, often unexpressed and perhaps not always even recognized by the authors, can be detected by detailed comparisons of
published formulae. The design of media has moved forward on a
broad front. From the first completely defined media capable of maintaining chick-embryo cells alive for periods of weeks (White, 1946,
1949; Morgan, Morton and Parker, 1950), the pattern has fanned out,
but elements of the early models can still be seen in the most up-to-date
and sophisticated formulations. From about 1950 onwards, medium
199 (Morgan, Morton and Parker, 1950), proposed for chick fibroblasts,
gained wide and rather indiscriminate acceptance as a synthetic
medium for all kinds of cells, and has been even more widely used with
biological supplements. But during the past decade many of the individual ingredients of particular media have been tested and retested,
against a wide spectrum of combinations of defined materials, and on
many cell systems. A medium designed for human cells has been
supplemented for use with cells of the Chinese hamster (Ham, 1960)
and one developed with chick fibroblasts applied to human muscle
(O'Steen, 1961). Out of all this work, some general principles and some
particular requirements can be discerned.
The basic ingredients of a synthetic medium are a salt mixture,
carbohydrate, amino acids and some vitamins. Compounds outside
these classes are often added, and can often be shown to have specific
beneficial effects on growth, differentiation or function. However,
none outside these classes is found to be an indispensable component
of all media.
C H A R I T Y W A Y M O U T H
The series of chemically defined media ( N C T C 107-117) designed
by Evans and Earle and their collaborators (Evans, Bryant, McQuilkin,
Fioramonti, Sanford, Westfall and Earle, 1956a,b; Evans, Fioramonti,
Sanford, Earle and Westfall, 1958; Earle, 1962) were based on analyses
of the amino-acid, amide and amine contents of serum and embryo
extract ultrafiltrates, and were to this extent imitative. "Practically all
commercially available vitamins were used in this medium" (Evans et
al., 1956a), on the comprehensive principle. These media have also
been very widely used (cf. Earle, 1962).
The synthetic media of Eagle (1955a,c,d, 1959) are "minimum
essential" or "basal" media, not complete media, and usually require
to be supplemented with small amounts of serum or serum ultrafiltrate.
However, cells from strain-L, clone 929, have been cultivated in a
modification of Eagle's basal medium in which the amino acids,
glutamine and eight vitamins are supplied at double the specified
concentrations (Merchant and Hellman, 1962).
The efforts of many individuals have contributed to the media
currently in use, and the flow and interchange of ideas between
laboratories, often unexpressed and perhaps not always even recognized by the authors, can be detected by detailed comparisons of
published formulae. The design of media has moved forward on a
broad front. From the first completely defined media capable of maintaining chick-embryo cells alive for periods of weeks (White, 1946,
1949; Morgan, Morton and Parker, 1950), the pattern has fanned out,
but elements of the early models can still be seen in the most up-to-date
and sophisticated formulations. From about 1950 onwards, medium
199 (Morgan, Morton and Parker, 1950), proposed for chick fibroblasts,
gained wide and rather indiscriminate acceptance as a synthetic
medium for all kinds of cells, and has been even more widely used with
biological supplements. But during the past decade many of the individual ingredients of particular media have been tested and retested,
against a wide spectrum of combinations of defined materials, and on
many cell systems. A medium designed for human cells has been
supplemented for use with cells of the Chinese hamster (Ham, 1960)
and one developed with chick fibroblasts applied to human muscle
(O'Steen, 1961). Out of all this work, some general principles and some
particular requirements can be discerned.
The basic ingredients of a synthetic medium are a salt mixture,
carbohydrate, amino acids and some vitamins. Compounds outside
these classes are often added, and can often be shown to have specific
beneficial effects on growth, differentiation or function. However,
none outside these classes is found to be an indispensable component
of all media.