38
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
Some of these difficulties and defects can be overcome by planting
the tissue on a second, smaller and circular coverslip, or similar support,
which is then sealed to the under-surface of the main coverslip by a drop
of medium or plasma. This second slip can act as a support for the
tissue and allow it to be washed in a relatively large volume of fresh
medium and replaced in a new hanging-drop chamber without risk
of infection (Maximow, 1925).
B. O B S E R V A T I O N A N D PERFUSION C H A M B E R S
(SLIDE CHAMBERS)
The stagnant conditions, the optical difficulties of the hollow-ground
slide, and the limited quantity of medium in the hanging-drop culture
have prompted numerous investigators in recent years to develop
slide chambers which overcome some of these difficulties (Pomerat,
1951; Mackaness, 1952; Christiansen, Danes, Allen and Leinfelder, 1953;
Buchsbaum and Kuntz, 1954; Rose, 1954; Richter and Woodward,
1955; Pulvertaft, Haynes and Groves, 1956; Paul, 1957; T o y and
Bardawil, 1958; Cruickshank, Cooper and Conran, 1959; Sharp,
1959; Sykes and Moore, 1960; and several others) (Fig. 2). These
chambers have optical surfaces both above and below the culture so
that the best conditions can be obtained for phase-contrast observation,
cinematography, etc. and so that it is possible to change or renew
the medium from time to time or even to bring about a slow continuous
perfusion. The latter, though theoretically desirable, has not always
been found to be very beneficial in practice, probably because of the
continuous strain which it imposes on the adaptive capacity of the
cells as they attempt to reach an equilibrium. Most workers are content to renew the medium periodically, and rely on the fact that the
medium : cell ratio in these chambers is usually considerably higher
than in the classical hanging-drop culture. Moreover, without the use
of antibiotics, which are not always desirable, it has been found rather
difficult in practice to maintain sterility when there are joints and taps
in the system and the proper pressures of fluid have to be maintained
in order to establish a continuous slow perfusion.
A great technical advance seems to have been made in these chambers by the introduction of silicone-rubber gaskets (Rose, 1954) to
separate the two coverslips, between which the cultures are planted.
An excellent seal is immediately formed which can afterwards be
readily penetrated by hypodermic needles for the introduction and
withdrawal of air, gas mixtures or fluids. The coverslip-gasket cultureunit is generally held firmly in some form of metal or Perspex container
and many such units can be stored, like slides, in the incubator. One
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
Some of these difficulties and defects can be overcome by planting
the tissue on a second, smaller and circular coverslip, or similar support,
which is then sealed to the under-surface of the main coverslip by a drop
of medium or plasma. This second slip can act as a support for the
tissue and allow it to be washed in a relatively large volume of fresh
medium and replaced in a new hanging-drop chamber without risk
of infection (Maximow, 1925).
B. O B S E R V A T I O N A N D PERFUSION C H A M B E R S
(SLIDE CHAMBERS)
The stagnant conditions, the optical difficulties of the hollow-ground
slide, and the limited quantity of medium in the hanging-drop culture
have prompted numerous investigators in recent years to develop
slide chambers which overcome some of these difficulties (Pomerat,
1951; Mackaness, 1952; Christiansen, Danes, Allen and Leinfelder, 1953;
Buchsbaum and Kuntz, 1954; Rose, 1954; Richter and Woodward,
1955; Pulvertaft, Haynes and Groves, 1956; Paul, 1957; T o y and
Bardawil, 1958; Cruickshank, Cooper and Conran, 1959; Sharp,
1959; Sykes and Moore, 1960; and several others) (Fig. 2). These
chambers have optical surfaces both above and below the culture so
that the best conditions can be obtained for phase-contrast observation,
cinematography, etc. and so that it is possible to change or renew
the medium from time to time or even to bring about a slow continuous
perfusion. The latter, though theoretically desirable, has not always
been found to be very beneficial in practice, probably because of the
continuous strain which it imposes on the adaptive capacity of the
cells as they attempt to reach an equilibrium. Most workers are content to renew the medium periodically, and rely on the fact that the
medium : cell ratio in these chambers is usually considerably higher
than in the classical hanging-drop culture. Moreover, without the use
of antibiotics, which are not always desirable, it has been found rather
difficult in practice to maintain sterility when there are joints and taps
in the system and the proper pressures of fluid have to be maintained
in order to establish a continuous slow perfusion.
A great technical advance seems to have been made in these chambers by the introduction of silicone-rubber gaskets (Rose, 1954) to
separate the two coverslips, between which the cultures are planted.
An excellent seal is immediately formed which can afterwards be
readily penetrated by hypodermic needles for the introduction and
withdrawal of air, gas mixtures or fluids. The coverslip-gasket cultureunit is generally held firmly in some form of metal or Perspex container
and many such units can be stored, like slides, in the incubator. One