Microtome is an instrument used in biological labs to cut thin slices or sections of different materials. There are several types available, and the rotary microtome is one among them.
The rotary microtome cuts the sections when the tissue blocks are moved in a rotary motion using a handwheel. It’s most commonly used for routine research works involving section cuttings from different specimens.
Figure: An illustration of the principle of sample movement in the rotary microtome.
Commercially available microtomes come in three forms: manual, semi-automotive, and automotive. The automated microtome machines have digital keys that control the speed of cutting specimens at your fingertips. It dramatically reduces the stress on your joints.
One similarity between the designs is that they are heavy, weighing about 40 to 60 pounds. It’s mainly to provide stability while cutting the sections of specimens and reduce generated vibrations during the process.
The advantages of rotary microtome include:
- Works well to obtain large numbers of serial sections of a specimen
- More stable while performing the cutting procedures
- Perfect for cutting paraffin-embedded tissues
- High precision level to produce thin sections
This article covers different parts of a rotary microtome, their functions, and factors you need to consider before buying one for your lab.
Parts of Rotary Microtome
The rotary microtome consists of the following parts:
- Microtome base plate: A platform with rails for securing the knife holder.
- Knife holder: It contains a knife tilt to adjust the knife angle and a face plate that orients ribbons toward the operator rather than away from the blade.
- Knife clamps hold the blade.
- Block holder: It ensures that the paraffin block is held in place and it stabilizes the specimen when it’s moved up and down to obtain tissue sections. It also contains a knob that allows the researchers to control the sections’ angles.
- Thickness gauge: It provides control over the thickness of the sections required from the specimen.
- Operating handle: It’s involved in moving the specimen in an up-and-down motion to obtain sections.
- Block adjustment: It fixes the paraffin block in its place based on how thick the block is.
- The angle of tilt adjustment: It allows control over the angle of the section that needs to be obtained from the specimen.
Figure: An image of an advanced high-tech rotary microtome.
Factors To Consider While Buying A Rotary Microtome
A variety of rotary microtomes are available for purchase; thus, getting the right rotary microtome for your lab workflows can be quite confusing. Here are some tips and factors to look over while purchasing a rotary microtome:
1. Good Section Quality
It is vital to ensure the quality of the sections when working on a research project or diagnosing a disease. A quality section means precision and stability of tissues and quality of different components of microtome, such as 
- Microtome stability to perform vibration-free sectioning
- Quality of knife holders, blades, thickness gauge, and specimen clamp
- Feeding-mechanism precision
When the specimen is orientated precisely with a zero-point reference, the block can be aligned quickly and re-cut as needed. Moreover, the electric cooling specimen device in microtomes helps you to obtain uniform sections. However, this feature is optional and isn’t present in all rotary microtomes.
2. Safety Features in Microtomes
When purchasing a microtome, safety should always be the most important consideration. When working with microtomes, you are close to sharp blades and at risk of cutting yourself.
Many accidents have been reported where lab personnel cut themselves while sectioning specimens, cleaning the machine, removing the blade, or exchanging blocks. 
That’s why its necessary to look for the following safety features when buying a rotary microtome:
- An object head that is adjustable depending on the clamp’s size and weight. It prevents accidental drops onto the blade during sectioning.
- With the handwheel safety locks, you can exchange blades and specimens easily and adjust specimen orientation without the object head moving.
- Blade ejectors and magnetic brushes make it easy to remove blades from blade holders without touching them.
- Microtomes equipped with safety guards enable you to cover the blade when they are not in use. As a result, the blades of the microtome can be cleaned and replaced without touching them.
- Ensure the coarse feed wheel is as close to the user as possible so that ergonomic comfort extends for a long time when rock trimming.
- Ergonomic microtomes allow users to adjust the microtome to their preferences, such as adjusting the coarse feed wheel. This reduces shoulder and back strain.
3. Type of Operation
Although manual machines are less expensive than automated ones, automated rotary microtomes have many advantages in terms of ergonomics and safety features:
- Using hand wheels repetitively for many hours can lead to discomfort and increase the risk of work-related musculoskeletal disorders (WMSDs). This is avoidable by using an automated rotary microtome which eliminates the need of using the handwheel.
- A built-in safety mechanism to prevent uncontrolled motorized sectioning. For example, sectioning should have two separate buttons to begin the process, this is available in most brands.
- During an emergency, the motor is immediately stopped by an emergency stop button located on the instrument housing or foot switch.
- Motorized rotary microtomes allow the hand-wheel handle to be centered so that the hands will not get caught on the turning wheel.
4. Brand/Supplier Reputation
Here are some questions to ask yourself before choosing a brand:
● Is it a reliable and recognized brand in the market?
Research the brand and see how long it has been in the industry, what its customers say about their buying experience, and if the company offers a high level of customer service, ranging from sales, delivery, and installation, to sales support.
● What do your peers have to say
Consult your peers whom you know working with a similar kind of lab workflow like yours or who have worked with microtomes. Ask them about their experience with the machine, visited shops/places, reliable options, and feature selection.
● Are maintenance services offered by the supplier?
See if they have qualified engineers for maintenance and repair processes. Also, check the warranty duration provided by the brands and if the supplier has the necessary parts of the equipment in their original forms.
Additionally, consider your budget, applications you need to perform, blade material, required section thickness, and type of knife (fixed or disposable) required for your lab procedures.
Related Read: Tips and Factors To Consider When Buying a Microtome
A rotary microtome is a precision tool used to cut sections with thicknesses ranging from 1 micron to 60 microns of a variety of specimens for a range of lab workflows.
It has a static knife and the object block moves in an up-and-down motion while spinning the handwheel to obtain the section.
The broad variety of rotary microtomes available makes it difficult to choose the right one for your lab. However, factors like the quality of sections obtainable, in-built safety features, budget, brand reputation, and materials used to build the instrument, should ultimately decide the exact product you go for.
Check out our S700A rotary microtome if you want an easy-to-operate, easy-to-clean microtome with high-end safety and technical features.
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- Microtomes And Types Of Microtome – Rotary Microtome, Base-Sledge Microtome, Cambridge Rocking Microtome & Freezing Microtome. Retrieved from https://paramedicsworld.com/histopathology-cytopathology-notes/microtomes/medical-paramedical-studynotes
- Instrumentation for Microtomy: Rotary Microtome Parts. Retrieved from https://www.labce.com/spg605374_instrumentation_for_microtomy_rotary_microtome_par.aspx
- S700A Rotary Microtome. Retrieved from https://conductscience.com/lab/s700a-rotary-microtome/
- 4 Tips for Buying a Microtome. Retrieved from https://www.leicabiosystems.com/en-in/life-sciences-and-research-solutions/resources/4-tips-to-buying-a-microtome/