5.1.
INTRODUCTORY REMARKS
137
genuity was employed in perfecting their edges. In spite of this there were
limitations and difficulties, and the discovery by Latta and Hartmann
(1950) that fracture edges of glass could be used was a much appreciated
boon.
The years between 1948 and 1952 thus were a time of ferment.
Bretschneider (1952) could review the history of ultrathin microtomy and
still discuss virtually every paper that dealt with tissue sections. Today,
not one of these papers is of more than historical interest. But for those of
us who experienced this period it was a time of intense activity. We were
confident that we could break through the many technical difficulties that
plagued us, for it was apparent that these were fundamentally of a minor
nature.
The definitive years were 1952 and 1953 when the first micrographs
that we would still regard as of good quality appeared from the Rockefeller
and Karolinska Institutes. Yet it is not really fair or possible to attribute
their success to any one advance. Rather, it represented the culmination of
improvements in microtomy, as well as a better understanding of problems of fixation, and also instrumental developments in the electron
microscope itself such as the biased gun, compensated pole-pieces, and
the use of apertures to increase specimen contrast.
An important event for the development of ultrathin microtomy was
the appearance of the commercial version of the Porter-Blum microtome.
This was first described in 1953 and became generally available that year.
This microtome quickly became the standard American instrument. The
ultramicrotome developed by Sjostrand (1953), which became available
commercially about the same time, enjoyed a somewhat comparable
position in Europe. It seemed that proximity to the source played a
large role in deciding the choice. These microtomes had sufficient reliability so that many laboratories could begin effective work. The introduction of these instruments completed the technical "breakthrough,"
and the electron microscopy of tissue sections has prospered ever since.
Currently we are seeing a second wave of interest in microtome design.
The beginning of this was evident at the Fourth International Congress
of Electron Microscopy in Berlin (1958) where more than a half dozen
new instruments were shown by commercial exhibitors. Although some
of these proved to be prototypes that were never actually marketed, about
the same number of microtomes were on sale at the time of the Fifth
International Congress in Philadelphia (1962). No doubt this interest in
new microtomes reflected a degree of dissatisfaction with what existed,
INTRODUCTORY REMARKS
137
genuity was employed in perfecting their edges. In spite of this there were
limitations and difficulties, and the discovery by Latta and Hartmann
(1950) that fracture edges of glass could be used was a much appreciated
boon.
The years between 1948 and 1952 thus were a time of ferment.
Bretschneider (1952) could review the history of ultrathin microtomy and
still discuss virtually every paper that dealt with tissue sections. Today,
not one of these papers is of more than historical interest. But for those of
us who experienced this period it was a time of intense activity. We were
confident that we could break through the many technical difficulties that
plagued us, for it was apparent that these were fundamentally of a minor
nature.
The definitive years were 1952 and 1953 when the first micrographs
that we would still regard as of good quality appeared from the Rockefeller
and Karolinska Institutes. Yet it is not really fair or possible to attribute
their success to any one advance. Rather, it represented the culmination of
improvements in microtomy, as well as a better understanding of problems of fixation, and also instrumental developments in the electron
microscope itself such as the biased gun, compensated pole-pieces, and
the use of apertures to increase specimen contrast.
An important event for the development of ultrathin microtomy was
the appearance of the commercial version of the Porter-Blum microtome.
This was first described in 1953 and became generally available that year.
This microtome quickly became the standard American instrument. The
ultramicrotome developed by Sjostrand (1953), which became available
commercially about the same time, enjoyed a somewhat comparable
position in Europe. It seemed that proximity to the source played a
large role in deciding the choice. These microtomes had sufficient reliability so that many laboratories could begin effective work. The introduction of these instruments completed the technical "breakthrough,"
and the electron microscopy of tissue sections has prospered ever since.
Currently we are seeing a second wave of interest in microtome design.
The beginning of this was evident at the Fourth International Congress
of Electron Microscopy in Berlin (1958) where more than a half dozen
new instruments were shown by commercial exhibitors. Although some
of these proved to be prototypes that were never actually marketed, about
the same number of microtomes were on sale at the time of the Fifth
International Congress in Philadelphia (1962). No doubt this interest in
new microtomes reflected a degree of dissatisfaction with what existed,