SEMINAR

MICROTOME

MICROTOMESMicrotomyMicrotomy is the means by which tissues can be

sectioned and attached to the surface so that examination by microscopy can take place.

The basic instrument used in microtomy is a microtome into which cutting tool is clamped. Microtome is the instrument which is used to cut

thin section of tissue.Microtome are machines that will advance

an object for a predetermined distance then slide the object to the cutting tool.

TYPES OF MICROTOMEThere are several types of microtome each designed for a specific purpose although many have a functional role.Excluding ultra microtome ,there are 5 basic types. named according to the mechanism.

Rotary microtomeRocking microtomeRotary rocking microtomeBase sledge microtomeSliding microtome Freezing microtome

ROTARY MICROTOMEParts:•Block holder•Knife clamps screws•Knife clamps•Block adjustment•Thickness gauge•Angle of tilt adjustment•Operating handle•Internal and external lock

• This is the most commonly used microtome for routines and research purpose.The rotary microtome is so called because of the rotary action of the hand wheel actuates.These machines sometimes called minor microtome after their inventor prof. Minot.

The rotary microtome is so called because of the rotary action of the hand wheel actuates.

These machines sometimes called minor microtome after their inventor prof. Minot.

This is the most commonly used microtome for routines and research purpose.

Here the knife is fixed & the tissue blocks moves up & down vertically in front of the knife.

Plane wedge knife is used.Thickness is adjusted by micrometer screws.The block moves forward to the knife at

presented thickness during the rotation of fly –wheel handle.

It has adjusting screws to make the tissue block parallel to the knife.

ADVANTAGESIt is heavier than rocking microtome.No vibration while cutting.It can be used for cutting hard tissues.The cutting angle of the knife is adjustable.The knife holder is movable. The ability to cope with very hard tissues ,

together with cutting good accurate section at 3mm gives the flexibility that is now required.

Electrically driven microtome can be used when the necessary to produce ribbons for serial reactions required.

This microtome are employed to their best advantage with resign embedded tissues.

Manual or electrically driven rotary microtome are successfully used in cryostats.

ROCKING MICROTOME•It is the oldest type of microtome.

•The name comes under the rocking action of the handle.

•The Cambridge rocking microtome was the most popular microtome.

•In this microtome knife is fixed &the block of the tissue moves through an arc to strike knife.

DISADVANTAGESThe size of the block that can be cut is

limited.It is a righter microtome , so it vibrates white

cutting.The cutting angle of the knife cannot be

adjusted.The sections cut curved when the block

moves through an arc.No serial section is possible.

ROTORY ROCKING MICROTOME

This is slightly more robust than the rocking microtome &has the advantage of producing a flat face to the tissue block.

Although they can be used for paraffin wax work, they are used more commonly in cryostat.

Most of them have retroactive mechanism which takes the tissue block away from the knife on the upward stroke.

SLEDGE MICROTOMEPARTS:Knife clampsBlock holderCourse adjustmentAngular lift adjustmentOperating handleThickness gaugeAdjustment rocking nutBlock adjustment screwSplit nut clamp

It is used to cut large paraffin block tissues like eye ball ,lungs brain and also for cutting hard tissue

It is a heavy microtome hence so stableKnife using is a plain wedge or Plano concaveHere the block is faced towards knife at

predetermined thicknessIt is also used for cutting colloid embedded

section or block Freezing stage is available on this machine

SLIDING MICROTOMEIn this type the knife is mode horizontally

against a fixed block.It is mainly used for cutting celloidin

embedded block & it is also used in paraffin backs embedding block.

ULTRA MICROTOMEUsed almost exclusively for electron

microscopy

FREEZING MICROTOME

Although other microtome can be modify for cutting frozen section, this type will

give the best results & is used almost universally.

VIBRATING MICROTOMEThis instrument has been designed to cut

tissues which has not been fixed , processed or frozen.

ADVANTAGESGreatest application in enzyme

histochemistry & ultra structure histochemistry.

Tissues are cut at very slow speed to avoid disintegration.

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