Botany:Microtome And Their Types

MICROTOME AND THEIR
TYPES
Whylgreen Jose
Assistant Professor
Department of Botany
St. Mary’s College Thrissur

Microtome and their types,Whylgreen Jose.St.Mary’s College
DEFINITIONS
A microtome (from the Greek mikros, meaning "small", and
temnein, meaning "to cut") is a tool used to cut extremely thin slices
of material, known as sections.
Important in science, microtomes are used in microscopy, allowing
for the preparation of samples for observation
Microtomes use steel, glass, or diamond blades depending upon the
specimen being sliced and the desired thickness of the sections being
cut.
Steel blades are used to prepare sections of animal or plant tissues
for light microscopy histology.

MICROTOMY
Microtomy - method for the preparation of thin sections for materials
such as bones, minerals and teeth, and an alternative to
electropolishing and ion milling.
Microtome sections can be made thin enough to section a human hair
across its breadth, with section thickness between 50 nm and 100 µm.

COMMEN EXAMPLES OF MICROTOMY
 Cryosections can also be used in immunohistochemistry as freezing
tissue stops degradation of tissue faster than using a fixative ,not alter
its chemical composition.
 Botanical Microtomy Technique: hard materials like wood, bone and
leather require a sledge microtome
 laser microtome, cuts the specimen with a femtosecond
laser,Contact-free and not require sample preparation techniques. Has
the ability to slice almost every tissue in its native state.

MICROTOME TYPES
Compresstome microtome
Uses a specimen syringe or "lipstick-like" tube to hold the
tissue.
The tissue specimen is completely embedded in agarose, and
the tissue is slowly and gently pressed out of the tube for the
vibrating blade to cut.
Advantages-
agarose embedding provides stability, which prevents uneven
slicing or shearing of tissue
blade doesn't push against the tissue
faster sectioning than most vibrating microtomes

sample is placed into a fixed holder (shuttle), which then moves
backwards and forwards across a knife.
Typical cut thickness achievable on a sledge microtome is between
1 and 60 µm.
Modern sled microtomes have the sled placed upon a linear
bearing, a design that allows the microtome to readily cut many
coarse sections
Sledge microtome

Operates with a staged rotary action, actual cutting is part of
the rotary motion.
In a rotary microtome, the knife is typically fixed in a horizontal
position.
The flywheel in many microtomes can be operated by hand.
Rotary microtome

For the cutting of frozen samples, many rotary microtomes
can be adapted to cut in a liquid-nitrogen chamber, in a so-
called cryomicrotome setup.
The reduced temperature allows the hardness of the sample
to be increased, such as by undergoing a glass transition,
which allows the preparation of semi-thin samples
Cryomicrotome

An ultramicrotome is a main tool of ultramicrotomy.
 It allows the preparation of extremely thin sections, with the
device functioning in the same manner as a rotational microtome,
but with very tight tolerances on the mechanical construction.
These extremely thin cuts are important for use with
transmission electron microscope (TEM) and serial block-face
scanning electron microscopy (SBFSEM)
Diamond knives and glass knives are used with
ultramicrotomes.
Ultramicrotome

The saw microtome is especially for hard materials such as
teeth or bones.
The microtome of this type has a recessed rotating saw,
which slices through the sample.
The minimal cut thickness is approximately 30 µm and can
be made for comparatively large samples.
Saw microtome

Vibrating microtome
The vibrating microtome operates by cutting using a vibrating
blade, allowing the resultant cut to be made with less pressure
than would be required for a stationary blade.
The vibrating microtome is usually used for difficult biological
samples
The cut thickness is usually around 30–500 µm for live tissue
and 10–500 µm for fixed tissue

REFERENCE
Peter Gray. Hand book of basic microtechnique. Mcgraw-
Hill.
K.V. Krishnamurthy.Methods in Plant histochemistry.
John E. Sass. Botanical Microtechnique,Oxford and IBH
Publishing

Botany:Microtome And Their Types

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