5. Sectioning
5.1. Introductory Remarks
Ultrathin sectioning has been possible for fifteen years. In retrospect,
of course, the early beginnings were relatively crude.
Attempts at ultrathin sectioning actually date back to the prewar
years and von Ardenne's (1939) effort to cut tapering wedges which would
be satisfactory in at least part of their area. Later, Richards and associates
(1942) and Sjostrand (1943) continued this approach but with little
success.
O'Brien and McKinley (1943) proposed that very high cutting speeds
were necessary if ultrathin sections were to be obtained, and they made
an effort to accomplish this by, in essence, attaching a razor blade to a
centrifuge rotor. Fullam and Gessler (1946) made a more serious effort to
design an instrument to operate on this principle, and to use very high
speeds. Such a microtome was actually marketed two years later with the
advertisements suggesting that the investigator could protect his investment by easily converting his microtome to an ultracentrifuge.
Pease and Baker (1948) showed that ultrathin sectioning at reasonable
cutting speeds was possible if a suitable embedding medium was used.
They were also able to modify a conventional microtome for this purpose.
Newman et al. (1949) introduced butylmethacrylate which became the
embedding medium of choice. These investigators also first employed a
thermal expansion principle to drive a microtome.
The next few years saw a variety of microtomes being developed in
different laboratories. Some of these were modifications of conventional
instruments, others were original designs; a few were commercially
marketed. Although it was apparent that these microtomes could be made
to work in the hands of their designers, in general they were not
sufficiently reliable to produce satisfactory sections in inexperienced
hands.
Microtomy was aided greatly when sections were floated away from the
knife edge on fluid surfaces, an idea perhaps first employed by Claude
(1948), but exploited by Gettner and Hillier (1950).
At first, steel knives were used for microtomy and considerable in136
5.1. Introductory Remarks
Ultrathin sectioning has been possible for fifteen years. In retrospect,
of course, the early beginnings were relatively crude.
Attempts at ultrathin sectioning actually date back to the prewar
years and von Ardenne's (1939) effort to cut tapering wedges which would
be satisfactory in at least part of their area. Later, Richards and associates
(1942) and Sjostrand (1943) continued this approach but with little
success.
O'Brien and McKinley (1943) proposed that very high cutting speeds
were necessary if ultrathin sections were to be obtained, and they made
an effort to accomplish this by, in essence, attaching a razor blade to a
centrifuge rotor. Fullam and Gessler (1946) made a more serious effort to
design an instrument to operate on this principle, and to use very high
speeds. Such a microtome was actually marketed two years later with the
advertisements suggesting that the investigator could protect his investment by easily converting his microtome to an ultracentrifuge.
Pease and Baker (1948) showed that ultrathin sectioning at reasonable
cutting speeds was possible if a suitable embedding medium was used.
They were also able to modify a conventional microtome for this purpose.
Newman et al. (1949) introduced butylmethacrylate which became the
embedding medium of choice. These investigators also first employed a
thermal expansion principle to drive a microtome.
The next few years saw a variety of microtomes being developed in
different laboratories. Some of these were modifications of conventional
instruments, others were original designs; a few were commercially
marketed. Although it was apparent that these microtomes could be made
to work in the hands of their designers, in general they were not
sufficiently reliable to produce satisfactory sections in inexperienced
hands.
Microtomy was aided greatly when sections were floated away from the
knife edge on fluid surfaces, an idea perhaps first employed by Claude
(1948), but exploited by Gettner and Hillier (1950).
At first, steel knives were used for microtomy and considerable in136