3. C O N S T R U C T I O N A N D USE OF S Y N T H E T I C M E D I A
101
were developing the techniques of Tissue Culture. After all, the difference between the physiologists who studied isolated muscles, nerves,
and organs, and the users of the new technique who studied the properties of surviving fragments or cell colonies, was initially more one of
scale than of objective. Survival in good condition of isolated parts, for
periods longer than the customary 1 or 2 h of the physiologists, is a
question of adequate nutrition, which in turn is bound up with the
problems of oxygenation, and with penetration of the bathing fluid
to the deeper parts. For longer study, therefore, smaller fragments
had to be used, to overcome the tendency to central necrosis. The
notion of using long, strip-shaped pieces, instead of the traditional
small cubes, was late in appearance (Earle, 1939). As evidence accumulated from work with biological media that not merely survival but
also proliferation and sustained function in vitro are feasible, so grew the
concept that an artificial environment for cells, completely replacing
the natural fluids, might be a real possibility. Simple modifications
of standard saline solutions, supplemented with amino acids or peptides (Lewis and Lewis, 1912) laid the foundation for most subsequent
significant work in developing chemically defined media. The farsighted aim of the Lewises has guided, and still directs, our thoughts
on these matters. Now, as in 1912, "Our aim here is of course to find
a medium that will permit of the continuous growth in large quantities
of tissues. Perhaps we may be able even to obtain selective media and
secure pure cultures of cells of one type, as the liver, heart muscle or
adrenal gland. One need not dwell upon the importance of such a
method for the study of the properties of tissues and cells both from
the anatomical and chemical point of view" (Lewis and Lewis, 1912).
The formulae of most of the balanced salt solutions used in tissue
culture (Ringer, 1886; Locke, 1895; Tyrode, 1910; Drew, 1923;
Pannett and Compton, 1924; Roffo, 1925; Gey and Gey, 1936;
Parker's glucosol, 1938; Simms and Sanders, 1942; Earle, 1943;
Hanks, 1948; White, 1949) have been listed before (Waymouth, 1954a,
Table II). The 1954 table should, however, be corrected by adding 5-0
mg/100 ml N a H 2 P 0 4 to Tyrode's solution, and 11 mg/100 ml N a 2 H P 0 4
and 10 mg/100 ml N a H 2 P 0 4 to Pannett and Compton's solution.
Stewart and Kirk (1954) also list most of the salt solutions current at
that time. Those still in common use are listed by Paul (1960) and
Parker (1961) and a short list is given in Table II (see p. 131). Several
marked differences in quoted formulae suggest the wisdom of returning
to the original descriptions and taking careful account of degrees of
hydration of the salts used, and of details in the methods of preparation.
The only significant additions to these lists of normal media are the Caand Mg-free salt solutions used in the preparation of cell suspensions by
101
were developing the techniques of Tissue Culture. After all, the difference between the physiologists who studied isolated muscles, nerves,
and organs, and the users of the new technique who studied the properties of surviving fragments or cell colonies, was initially more one of
scale than of objective. Survival in good condition of isolated parts, for
periods longer than the customary 1 or 2 h of the physiologists, is a
question of adequate nutrition, which in turn is bound up with the
problems of oxygenation, and with penetration of the bathing fluid
to the deeper parts. For longer study, therefore, smaller fragments
had to be used, to overcome the tendency to central necrosis. The
notion of using long, strip-shaped pieces, instead of the traditional
small cubes, was late in appearance (Earle, 1939). As evidence accumulated from work with biological media that not merely survival but
also proliferation and sustained function in vitro are feasible, so grew the
concept that an artificial environment for cells, completely replacing
the natural fluids, might be a real possibility. Simple modifications
of standard saline solutions, supplemented with amino acids or peptides (Lewis and Lewis, 1912) laid the foundation for most subsequent
significant work in developing chemically defined media. The farsighted aim of the Lewises has guided, and still directs, our thoughts
on these matters. Now, as in 1912, "Our aim here is of course to find
a medium that will permit of the continuous growth in large quantities
of tissues. Perhaps we may be able even to obtain selective media and
secure pure cultures of cells of one type, as the liver, heart muscle or
adrenal gland. One need not dwell upon the importance of such a
method for the study of the properties of tissues and cells both from
the anatomical and chemical point of view" (Lewis and Lewis, 1912).
The formulae of most of the balanced salt solutions used in tissue
culture (Ringer, 1886; Locke, 1895; Tyrode, 1910; Drew, 1923;
Pannett and Compton, 1924; Roffo, 1925; Gey and Gey, 1936;
Parker's glucosol, 1938; Simms and Sanders, 1942; Earle, 1943;
Hanks, 1948; White, 1949) have been listed before (Waymouth, 1954a,
Table II). The 1954 table should, however, be corrected by adding 5-0
mg/100 ml N a H 2 P 0 4 to Tyrode's solution, and 11 mg/100 ml N a 2 H P 0 4
and 10 mg/100 ml N a H 2 P 0 4 to Pannett and Compton's solution.
Stewart and Kirk (1954) also list most of the salt solutions current at
that time. Those still in common use are listed by Paul (1960) and
Parker (1961) and a short list is given in Table II (see p. 131). Several
marked differences in quoted formulae suggest the wisdom of returning
to the original descriptions and taking careful account of degrees of
hydration of the salts used, and of details in the methods of preparation.
The only significant additions to these lists of normal media are the Caand Mg-free salt solutions used in the preparation of cell suspensions by