80
A . M O S C O N A , O . A . T R O W E L L A N D E . N . W l L L M E R
F. P E R F U S I O N M E T H O D S
In all the preceding methods the medium is stationary and metabolic
exchanges proceed solely by diffusion, except in Medawar's method
(Fig. 8b) where the flask is shaken. In theory, metabolic exchanges
and particularly oxygen supply could be considerably improved by
stirring or circulating the medium. The ideal would be to perfuse the
blood vessels of the organ with culture medium. Carrel and Lindbergh
(1938) constructed an elaborate pump which imitated the pulsatile
flow obtaining in arteries, and they claimed to have kept thyroid glands
and ovaries of cats alive for up to 3 weeks by perfusing the main artery
with oxygenated serum. But, as no one has been able to obtain any
similar results, this claim must be discounted. Other workers have always
found that the smaller blood vessels disintegrated after a few hours
perfusion.
The remaining method is to use organ cultures of the size already
described and maintain a continuous flow of medium around them.
By common usage this procedure is called "perfusion", but more correctly it is "circumfusion". De Haan (1937) described a relatively
simple apparatus for the circumfusion of tissue cultures, and De Jong
and De Haan (1943) used it for culture of the stomach-oesophagustrachea complex of chick embryos. The apparatus simply maintained
a steady flow of fresh medium from a reservoir past the cultures.
Schwartz (1960) used an apparatus similar in principle but more
refined in construction for continuous circumfusion of the isolated
optic lens (Vol. 2, Chapter 10). With this he was able to monitor the pH,
the Eh, and the concentrations of oxygen, glucose and lactate in the
incoming and outgoing fluid over a culture period of 3 days.
These circumfusion methods are useful and indeed very desirable for
certain metabolic and pharmacological experiments, but there is no
evidence that cultures survive any better under these conditions than
on the surface of a stationary medium. There is in fact some evidence
that survival is worse, probably because essential substances leak from
the cells and are washed away or because the cultures are given no
chance to "condition" the medium in their immediate vicinity. In
the present author's experience, with culture of mature organs, any
rapid movement of the medium whether by shaking, stirring or continuous circumfusion is harmful. The most that the cultures will stand
is a very gentle seeping of medium past them, and this did not improve
their survival (Trowell, 1961a).
G. L I M I T I N G F A C T O R S IN O R G A N C U L T U R E
The present methods of organ culture are adequate for fairly short-
A . M O S C O N A , O . A . T R O W E L L A N D E . N . W l L L M E R
F. P E R F U S I O N M E T H O D S
In all the preceding methods the medium is stationary and metabolic
exchanges proceed solely by diffusion, except in Medawar's method
(Fig. 8b) where the flask is shaken. In theory, metabolic exchanges
and particularly oxygen supply could be considerably improved by
stirring or circulating the medium. The ideal would be to perfuse the
blood vessels of the organ with culture medium. Carrel and Lindbergh
(1938) constructed an elaborate pump which imitated the pulsatile
flow obtaining in arteries, and they claimed to have kept thyroid glands
and ovaries of cats alive for up to 3 weeks by perfusing the main artery
with oxygenated serum. But, as no one has been able to obtain any
similar results, this claim must be discounted. Other workers have always
found that the smaller blood vessels disintegrated after a few hours
perfusion.
The remaining method is to use organ cultures of the size already
described and maintain a continuous flow of medium around them.
By common usage this procedure is called "perfusion", but more correctly it is "circumfusion". De Haan (1937) described a relatively
simple apparatus for the circumfusion of tissue cultures, and De Jong
and De Haan (1943) used it for culture of the stomach-oesophagustrachea complex of chick embryos. The apparatus simply maintained
a steady flow of fresh medium from a reservoir past the cultures.
Schwartz (1960) used an apparatus similar in principle but more
refined in construction for continuous circumfusion of the isolated
optic lens (Vol. 2, Chapter 10). With this he was able to monitor the pH,
the Eh, and the concentrations of oxygen, glucose and lactate in the
incoming and outgoing fluid over a culture period of 3 days.
These circumfusion methods are useful and indeed very desirable for
certain metabolic and pharmacological experiments, but there is no
evidence that cultures survive any better under these conditions than
on the surface of a stationary medium. There is in fact some evidence
that survival is worse, probably because essential substances leak from
the cells and are washed away or because the cultures are given no
chance to "condition" the medium in their immediate vicinity. In
the present author's experience, with culture of mature organs, any
rapid movement of the medium whether by shaking, stirring or continuous circumfusion is harmful. The most that the cultures will stand
is a very gentle seeping of medium past them, and this did not improve
their survival (Trowell, 1961a).
G. L I M I T I N G F A C T O R S IN O R G A N C U L T U R E
The present methods of organ culture are adequate for fairly short-