6.11.
SERIAL SECTIONS
213
a portion of this is picked up free hand and centered across a single hole,
one obtains good preparations without special problems. More elegant
methods of orienting serial sections in picking them up have been described, however. These involve some of the principles and equipment of
simple micromanipulation.
Gay and Anderson (1954) were perhaps the first to report on a long
series of sections. Their ribbons were picked up on a Formvar film supported by a small wire loop. Their grids were placed on a plastic assembly on top of an adjustable condenser in a standard microscope. By racking down the condenser, the grid was kept below the stage level while
suitable alignment was achieved with the ribbon on the loop. Then contact was established by lifting the condenser assembly.
A disadvantage of Gay and Anderson's method is that fairly heavy supporting films are required. This can be obviated if floating sections are
picked up directly upon grids. Perhaps the simplest way of obtaining a
large measure of mechanical control is to attach a simple platform to a
low power microscope objective. The platform, which holds the grid,
should be just below the focal level of the objective, but close enough to
this plane so that an out-of-focus image of the grid slots can be seen. The
grid is at first below the surface of the fluid, and the floating ribbon is
aligned above it. This may be done freehand or with a simple manipulator. The screen is then lifted to pick up the ribbon simply by racking
up the microscope barrel.
Barnes and Chambers (1961) describe how an extremely simple and
inexpensive micromanipulator can be made. They use several glass microscope slides, lubricated with a viscous grease, sliding upon one another and oriented in different planes. An arm attached with epoxy glue
carries a platinum loop. A ribbon of sections is picked up on a Formvar
film stretched across the loop. The manipulator serves to transfer the ribbon to a grid mounted on a post while being observed with a binocular
microscope.
Westfall and Healy (1962) describe a brass device which can be fitted
into a knife trough. This is designed to hold a prepared grid under water
very close to the knife edge, and incorporates a capillary connection to
a fluid reservoir and a sensitive control so that the fluid level in the
trough can be varied accurately at will. As a ribbon of sections leaves the
knife edge it passes over the grid. When it is properly positioned the fluid
level is dropped and the sections drop down upon the grid surface.
SERIAL SECTIONS
213
a portion of this is picked up free hand and centered across a single hole,
one obtains good preparations without special problems. More elegant
methods of orienting serial sections in picking them up have been described, however. These involve some of the principles and equipment of
simple micromanipulation.
Gay and Anderson (1954) were perhaps the first to report on a long
series of sections. Their ribbons were picked up on a Formvar film supported by a small wire loop. Their grids were placed on a plastic assembly on top of an adjustable condenser in a standard microscope. By racking down the condenser, the grid was kept below the stage level while
suitable alignment was achieved with the ribbon on the loop. Then contact was established by lifting the condenser assembly.
A disadvantage of Gay and Anderson's method is that fairly heavy supporting films are required. This can be obviated if floating sections are
picked up directly upon grids. Perhaps the simplest way of obtaining a
large measure of mechanical control is to attach a simple platform to a
low power microscope objective. The platform, which holds the grid,
should be just below the focal level of the objective, but close enough to
this plane so that an out-of-focus image of the grid slots can be seen. The
grid is at first below the surface of the fluid, and the floating ribbon is
aligned above it. This may be done freehand or with a simple manipulator. The screen is then lifted to pick up the ribbon simply by racking
up the microscope barrel.
Barnes and Chambers (1961) describe how an extremely simple and
inexpensive micromanipulator can be made. They use several glass microscope slides, lubricated with a viscous grease, sliding upon one another and oriented in different planes. An arm attached with epoxy glue
carries a platinum loop. A ribbon of sections is picked up on a Formvar
film stretched across the loop. The manipulator serves to transfer the ribbon to a grid mounted on a post while being observed with a binocular
microscope.
Westfall and Healy (1962) describe a brass device which can be fitted
into a knife trough. This is designed to hold a prepared grid under water
very close to the knife edge, and incorporates a capillary connection to
a fluid reservoir and a sensitive control so that the fluid level in the
trough can be varied accurately at will. As a ribbon of sections leaves the
knife edge it passes over the grid. When it is properly positioned the fluid
level is dropped and the sections drop down upon the grid surface.