72
A . M O S C O N A , O. A . T R O W E L L A N D E . N. W I L L M E R
Both embryonic and mature organs are generally cultured on the
surface of a relatively large volume of stationary medium and this is
the basic principle of organ-culture technique. Embryonic organs
may require a particularly nutritive medium, while most mature
organs require an oxygen gas-phase. These are the principle features
which govern the design of the apparatus.
The various technical methods will now be outlined, proceeding
from the earliest to the most recent so as to show how they evolved.
B. O R G A N F R A G M E N T S SUSPENDED IN MEDIUM
Loeb (1897) cultured small pieces of adult rabbit liver, kidney,
thyroid and ovary suspended in a small volume of serum or plasmaclot in a test tube, and found that normal histological structure was
maintained for up to 3 days. This is the first recorded organ culture
and it antedates Harrison's introduction of tissue culture by ten years.
Loeb and Fleisher (1919) showed that the tube must be filled with
oxygen, otherwise the cultures become necrotic in the middle. It is
surprising that they did not think of the further step of putting the
cultures on or near the surface of the medium, and that it was left to
Fischer in 1928 to show how different tissues respond to such treatment.
Parker (1936) revived the principle of this method and cultured small
fragments of various adult organs in a shallow layer of fluid medium in
a flat-bottomed flask which was filled with 80% oxygen (Fig. 8a).
The tissue : medium ratio was much higher than that used nowadays;
75 fragments, total weight 100 mg, were cultured in 2 ml medium in
a 70 ml flask. The chief importance of Parker's work is that he demonstrated by experiment the high oxygen and glucose requirements of
adult tissues in vitro. The method is unsatisfactory in practice because
if the flask is unshaken the cultures settle on the bottom where their
oxygen supply is poor, and consequently only very tiny fragments can
be used, while if the flask is shaken to improve oxygenation the cultures
soon disintegrate. Hence the method has not been generally used except
for the culture of tangential slices of adult skin.
Skin is a peculiarly suitable tissue for two reasons. First, the epidermal
surface is non-wettable, or can be made so by smearing with Vaseline,
so the slices float on the medium, raw surface downwards. Second,
skin is tough enough to withstand shaking of the vessel. Medawar
(1948), who introduced this method of skin culture, floated 2-3 small
slices of rabbit ear-skin on 3 ml of serum-saline in a tube or flask which
was filled with about 70°/o oxygen and gently shaken (Fig. 8b). In
point of fact, since the slices float on the medium, their oxygen supply
is good enough without shaking, and Cruikshank (1951) has cultured
A . M O S C O N A , O. A . T R O W E L L A N D E . N. W I L L M E R
Both embryonic and mature organs are generally cultured on the
surface of a relatively large volume of stationary medium and this is
the basic principle of organ-culture technique. Embryonic organs
may require a particularly nutritive medium, while most mature
organs require an oxygen gas-phase. These are the principle features
which govern the design of the apparatus.
The various technical methods will now be outlined, proceeding
from the earliest to the most recent so as to show how they evolved.
B. O R G A N F R A G M E N T S SUSPENDED IN MEDIUM
Loeb (1897) cultured small pieces of adult rabbit liver, kidney,
thyroid and ovary suspended in a small volume of serum or plasmaclot in a test tube, and found that normal histological structure was
maintained for up to 3 days. This is the first recorded organ culture
and it antedates Harrison's introduction of tissue culture by ten years.
Loeb and Fleisher (1919) showed that the tube must be filled with
oxygen, otherwise the cultures become necrotic in the middle. It is
surprising that they did not think of the further step of putting the
cultures on or near the surface of the medium, and that it was left to
Fischer in 1928 to show how different tissues respond to such treatment.
Parker (1936) revived the principle of this method and cultured small
fragments of various adult organs in a shallow layer of fluid medium in
a flat-bottomed flask which was filled with 80% oxygen (Fig. 8a).
The tissue : medium ratio was much higher than that used nowadays;
75 fragments, total weight 100 mg, were cultured in 2 ml medium in
a 70 ml flask. The chief importance of Parker's work is that he demonstrated by experiment the high oxygen and glucose requirements of
adult tissues in vitro. The method is unsatisfactory in practice because
if the flask is unshaken the cultures settle on the bottom where their
oxygen supply is poor, and consequently only very tiny fragments can
be used, while if the flask is shaken to improve oxygenation the cultures
soon disintegrate. Hence the method has not been generally used except
for the culture of tangential slices of adult skin.
Skin is a peculiarly suitable tissue for two reasons. First, the epidermal
surface is non-wettable, or can be made so by smearing with Vaseline,
so the slices float on the medium, raw surface downwards. Second,
skin is tough enough to withstand shaking of the vessel. Medawar
(1948), who introduced this method of skin culture, floated 2-3 small
slices of rabbit ear-skin on 3 ml of serum-saline in a tube or flask which
was filled with about 70°/o oxygen and gently shaken (Fig. 8b). In
point of fact, since the slices float on the medium, their oxygen supply
is good enough without shaking, and Cruikshank (1951) has cultured