4
1. LABORATORY ORGANIZATION AND MANAGEMENT
RCA EMU-1 and -2 series instruments, and the newer EML, can be
modernized with accessory equipment of this sort purchased from the
Canal Instrument Company of Bethesda, Maryland. The cost is about
$1000 and $1200, respectively, but is an investment that must be regarded
as essential for tissue work. In addition, any microscope used must have
a magnifying viewer for accurate focus. This should be a x7 or XlO
power microscope with a very long working distance. A binocular dissecting microscope head is most satisfactory if it can be fitted to the
instrument.
Almost all tissue studies with ultrathin sections can be done very
satisfactorily with an electron microscope operating at an accelerating
potential of 50 kv. Indeed the reduced contrast resulting from the use of
higher voltages generally works to one's disadvantage. There are problems
with some of the newer embedding media, however, which can be partly
solved by using fairly thick sections with greater accelerating voltages.
Thick sections are particularly pertinent for autoradiography (Chapter 7.
12), so that one cannot categorically say that high voltage microscopes will
not prove importantly useful. It should be noted, however, that one
cannot easily switch back and forth from one accelerating voltage to another without correcting alignment and compensation, so that in practice
a microscope almost has to be used for extended periods of time at a
particular voltage.
It is desirable that the electron microscope have certain features that
may only be available as accessories. An externally adjustable condenser
aperture is useful since apertures of various sizes can be substituted easily
to meet varying requirements. The electron microscope must have a fast
shutter mechanism of some sort (so that 0.5-1 second exposures can be
made). It is desirable that this be an electrically timed shutter. A photometer can be added as an accessory to some microscopes and is a useful
adjunct. A microscope equipped with a modulating and normalizing system for eliminating lens hysteresis is useful, particularly if accurate
mensuration is anticipated.
Ultramicrotomes are discussed in Chapter 5. It is essential that any
instrument used be fitted with a binocular dissecting microscope. This
can be mounted on a separate stand with a long horizontal arm, or it can
be incorporated into the microtome on a suitable bracket.
At least one additional binocular dissecting microscope must be put on
the essential list. It is important that its head be tiltable in relation to its
stage so that sections can be examined obliquely. This is so used to
1. LABORATORY ORGANIZATION AND MANAGEMENT
RCA EMU-1 and -2 series instruments, and the newer EML, can be
modernized with accessory equipment of this sort purchased from the
Canal Instrument Company of Bethesda, Maryland. The cost is about
$1000 and $1200, respectively, but is an investment that must be regarded
as essential for tissue work. In addition, any microscope used must have
a magnifying viewer for accurate focus. This should be a x7 or XlO
power microscope with a very long working distance. A binocular dissecting microscope head is most satisfactory if it can be fitted to the
instrument.
Almost all tissue studies with ultrathin sections can be done very
satisfactorily with an electron microscope operating at an accelerating
potential of 50 kv. Indeed the reduced contrast resulting from the use of
higher voltages generally works to one's disadvantage. There are problems
with some of the newer embedding media, however, which can be partly
solved by using fairly thick sections with greater accelerating voltages.
Thick sections are particularly pertinent for autoradiography (Chapter 7.
12), so that one cannot categorically say that high voltage microscopes will
not prove importantly useful. It should be noted, however, that one
cannot easily switch back and forth from one accelerating voltage to another without correcting alignment and compensation, so that in practice
a microscope almost has to be used for extended periods of time at a
particular voltage.
It is desirable that the electron microscope have certain features that
may only be available as accessories. An externally adjustable condenser
aperture is useful since apertures of various sizes can be substituted easily
to meet varying requirements. The electron microscope must have a fast
shutter mechanism of some sort (so that 0.5-1 second exposures can be
made). It is desirable that this be an electrically timed shutter. A photometer can be added as an accessory to some microscopes and is a useful
adjunct. A microscope equipped with a modulating and normalizing system for eliminating lens hysteresis is useful, particularly if accurate
mensuration is anticipated.
Ultramicrotomes are discussed in Chapter 5. It is essential that any
instrument used be fitted with a binocular dissecting microscope. This
can be mounted on a separate stand with a long horizontal arm, or it can
be incorporated into the microtome on a suitable bracket.
At least one additional binocular dissecting microscope must be put on
the essential list. It is important that its head be tiltable in relation to its
stage so that sections can be examined obliquely. This is so used to