Microtome in Light Microscope Development

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Questions and Answers

What was the primary challenge faced by early light microscope developers when preparing sections from plants and animals?

Making clean reproducible cuts on the order of 100 μm (correct)

Achieving high-quality images

Acquiring sufficient light transmission

Selecting suitable metal blades

What is the main purpose of a microtome?

To cut extremely thin sections from a sample for histology or pathology applications (correct)

To examine samples using electron radiation

To transmit light through samples

To magnify samples for observation

What is the term for the process of producing extremely thin slices of material using a microtome?

Pathology

Histology

Micro sectioning (correct)

Microscopy

What is the name of the most widely used type of microtome?

Rotary microtome Signup and view all the answers

Why is the rotary microtome suitable for paraffin-embedded sections?

Because it uses a stationary knife and the block is moved up and down Signup and view all the answers

What is the significance of microtomes in science?

They are used to prepare samples for observation under transmitted light or electron radiation Signup and view all the answers

What type of blades are used in microtomes?

Special metal, glass, or diamond blades, depending on the type of specimen and the desired thickness Signup and view all the answers

What is the origin of the word 'microtome'?

From the Greek 'mikros', meaning 'small', and 'temnein', meaning 'to cut' Signup and view all the answers

When should the safety lock be used in a microtomist?

Anytime the microtomist is not actively sectioning paraffin blocks Signup and view all the answers

What is the primary function of a water bath in a laboratory?

To incubate samples over a period of time at a constant temperature Signup and view all the answers

What is the purpose of the thermometer in a water bath?

To measure the temperature of the water Signup and view all the answers

What type of water bath is ideal for uses when temperature uniformity and regularity is critical?

Circulating water bath Signup and view all the answers

What is the main difference between a circulating water bath and a non-circulating water bath?

The method of temperature control Signup and view all the answers

What is the additional feature of a shaking water bath?

Control for shaking, which moves liquids from one place to another Signup and view all the answers

What is the principle of a water bath?

Heat applied to the sample using the heater Signup and view all the answers

What is the purpose of the thermostat or regulator in a water bath?

To maintain a constant temperature Signup and view all the answers

What is the primary mechanism by which dry heat sterilization destroys microorganisms?

By oxidizing molecules Signup and view all the answers

Which of the following materials can be sterilized using dry heat sterilization?

Glassware, powders, and oils Signup and view all the answers

What is the main advantage of using a dry heat cabinet?

It is a non-toxic and environmentally friendly method Signup and view all the answers

What is the primary limitation of dry heat sterilization?

It is a time-consuming method due to slow heat penetration Signup and view all the answers

What is the primary purpose of PCR?

To amplify a specific sequence of DNA Signup and view all the answers

What is the outcome of PCR?

Thousands to millions of copies of the target DNA sequence Signup and view all the answers

What is the main difference between dry heat sterilization and moist heat sterilization?

Dry heat sterilization requires higher temperatures and longer exposure times Signup and view all the answers

What type of instrument is commonly sterilized using dry heat sterilization?

All of the above Signup and view all the answers

What is the main advantage of using a microtome in cutting serial sections?

It provides a more stable cutting process due to its heavier weight Signup and view all the answers

What is the function of the block holder in a microtome?

To hold the paraffin block in place and move it up and down with each revolution Signup and view all the answers

What is the purpose of the knife tilt in a microtome?

To adjust the knife angle Signup and view all the answers

What is the function of the coarse handwheel in a microtome?

To move the block holder towards or away from the knife Signup and view all the answers

What is the range of micron settings for section thickness on most microtomes?

1 to 60 microns Signup and view all the answers

What is the purpose of the advancement hand wheel in a microtome?

To move the block holder towards the knife at the specified microns Signup and view all the answers

What is the disadvantage of using a microtome?

It is not suitable for cutting hard blocks of hard tissue Signup and view all the answers

What is the function of the knife holder base in a microtome?

To anchor the knife holder to the microtome stage Signup and view all the answers

What is the purpose of staining molecules in the gel after electrophoresis?

To make the molecules visible Signup and view all the answers

What type of light can be used to visualize fluorescing molecules in the gel?

Ultraviolet light Signup and view all the answers

What is the main application of electrophoresis?

To separate macromolecules Signup and view all the answers

What is the name of the Russian botanist credited with the development of chromatography?

Tswet Signup and view all the answers

What is the principle of chromatography based on?

The principle of partition of solute between two phases Signup and view all the answers

What is the mobile phase in chromatography?

A compound used to separate components in a mixture Signup and view all the answers

What is the common name of the father of chromatography?

The Father of Chromatography Signup and view all the answers

What is the purpose of the stationary phase in chromatography?

To provide a porous solid matrix for the components to move through Signup and view all the answers

Study Notes

Microtome

Machines that cut extremely thin sections from a sample for applications in histology or pathology
Use special metal, glass, or diamond blades, depending on the type of specimen and the desired thickness
Consist of a blade holding unit with a blade holder and clamped blade, the clamp, an advancing mechanism, and a mechanism for adjusting section thickness
Types of microtomes: rotary, rocking, base-sledge sliding, freezing vibrating, saw, cryostat, ultra-microtome

Rotary Microtome

Most widely used, also called Minot microtome, after its inventor Professor Minot
The knife is stationary and the block is moved up and down in a vertical plane by the rotary action of the hand wheel
Suitable for paraffin-embedded sections
Advantages: ideal for cutting serial sections, heavier so more stable, the heavier knife is used so less vibration, the cutting angle (tilt) of the knife is adjustable, ability to cope with harder tissue
Disadvantage: not suitable for hard blocks of hard tissue

Parts of Microtome

Block holder: holds the paraffin block in place
Microtome base plate or stage: a plate form that has rails that secure the knife holder base
Knife holder base: a part that anchors the knife holder to the microtome stage
Knife holder: comprised of several components including the blade clamp that holds the blade, the knife tilt for adjusting the knife angle, and the face plate that guides the ribbons away from the blade and towards the operator
Coarse handwheel: moves the block holder either toward the knife or away from the knife
Micron adjustment: micron settings for section thickness can range from 1 to 60 microns on most microtomes
Advancement hand wheel: turns in one direction and advances the block toward the knife at the specified microns

Water Bath

A laboratory instrument that maintains a constant temperature
Used to incubate samples over a period of time at a constant temperature
Parts of water bath: container or tank bath, heater, thermometer, thermostat or regulator
Types of water bath: circulating water bath, non-circulating water bath, shaking water bath

PCR (Polymerase Chain Reaction)

A technique used in molecular biology to amplify a single copy or a few copies of a segment of DNA across several orders of magnitude
Generates thousands to millions of copies of a particular DNA sequence
Used to take a specific sequence of DNA of small amount and amplify it for further testing

Chromatography

A physical process where the components (solutes) of a sample mixture are separated as a result of their differential distribution between stationary and mobile phases
Stationary phase: a porous solid matrix through which the sample contained in the mobile phase moves
Mobile phase: a compound used to separate components in a mixture, this phase can move along with the components
Principle: usually based on the principle of partition of solute between two phases

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Description

Learn about the importance of microtomes in preparing samples for light microscopy, from manual sectioning to clean reproducible cuts.