In various fields, such as pathology and histology, preserving tissue samples is vital. To keep samples intact, researchers must freeze them immediately upon collection and maintain this preserved state while studying the samples. Instruments like cryostat microtomes make these processes possible.
What Is a Cryostat?
A cryostat is an instrument that maintains a constant low temperature to freeze and preserve samples like liquids or tissues. The term “cryostat” is also used as shorthand for “cryostat microtome.” A standard microtome is a cutting instrument used for a process called microsectioning — producing extremely thin slices of a sample, usually tissue samples, called sections. A cryostat microtome allows researchers to section tissue samples in a controlled, cryogenic environment.
As a result, cryostats are invaluable for research fields. They allow researchers to keep samples intact and obtain thin enough samples to study microscopically and make rapid diagnoses for various medical conditions or diseases.
Cryostat Components
Cryostats have different components that make cryogenic microsectioning possible:
- Freezing chamber and cryogenic gas: The freezing chamber and cryogenic gas or fluids allow the cryostat to maintain constantly low temperatures. Researchers may use liquid helium and liquid nitrogen for cooling applications. The freezing chamber is what contains the microtome and cools it while it is sectioning.
- Specimen check: Specimen checks mount the samples on the microtome for sectioning.
- Microtome: A microtome is a cutting instrument mounted with a sharp, fixed blade. Its mechanism moves the samples toward the blade.
- Blade holder: The blade holder clamps either disposable or reusable blades into position.
- Anti-roll plates: Anti-roll plates prevent the sections from curling after they have been cut.
- Peltier stage: This device removes heat from the cryostat chamber.
- Control panel: The control panel makes it possible to operate the instrument. It includes on/off switches, a timer, temperature control and other features.
How to Use a Cryostat
Before sectioning a sample in the cryostat, the user must prepare both the sample and the cryostat. Prepping the cryostat may consist of running a disinfection protocol and setting the desired chamber temperature. While the chamber is cooling, the pathologist may then freeze the tissue sample. Tissue must be frozen and immersed in a specialized solution to support its cellular morphology during sectioning; if its cellular structure crumbles, the tissue can't be stained and examined properly.
Microtomy
Once the sample is embedded and the chamber is at its set temperature, the pathologist can then mount the sample to its holder on the microtome and begin sectioning it. Sectioning may be performed manually with the handwheel on the side of the cryostat or, in the case of more sophisticated units, with a motorized microtome that sections automatically.
Cleanup
Microtomy can be messy — after sectioning a sample there may be small scraps littering the chamber. The user can sweep up the shavings manually or, if waste trays are installed, empty the trays. If one decides to remove the tray, one must allow the chamber temperature to equilibrate with the room's ambient temperature — otherwise, the tray will condensate when removed from the chamber and then freeze to the chamber once placed back in. Alternatively, the user can also vacuum them up if their cryostat is equipped with a vacuum assist feature.
Additional Features and How They Work
Many cryostats come with advanced features to make disinfection easier, quick-freeze samples, and more. Here are a few of the options you can find on cryostats at New Life Scientific:
Vacuum Assist
Vacuum systems keep tissue sections flat, which ensures they'll be suitable for coverslipping onto microscope slides later. Pulling on the section with a light vacuum keeps it taut and won't bunch up or fold as it is sliced. As stated earlier, vacuum assist tubes can also be used to quickly and easily clean up scraps of tissue.
Automatic Disinfection
For the sake of safety and convenience, many cryostats come with automatic chamber disinfection systems built in. There are two types of automatic disinfection:
- Fumigation: Fumigation systems are ideal for deep cleaning. These systems release a gas, usually O2 or peroxide, that expands to fill every part of the chamber and wipe out any pathogens. While highly effective, fumigation systems are far from perfect. They take a long time to complete a cycle, and there is risk posed to those working around the cryostat should the gas start leaking.
- UV disinfection: In UV disinfection systems, a bulb seated within the chamber illuminates and coats every exposed surface with ultraviolet light that eradicates any pathogens that could be lurking. Ultraviolet disinfection is fast, efficient, and completely safe for those near the cryostat. However, it's not as thorough as fumigation systems — if any angle of the chamber is shielded from light, it won't be disinfected.
Automatic Motorized Sectioning
Motorized cryostat microtomes, also found on benchtop microtomes like the Tissue-Tek AutoSection, offer fully automated sectioning that frees up valuable time for the pathologist and ensures consistent sections.
Cryostat Applications
Cryostats makes progress and breakthroughs possible in various fields:
- Histopathology: This is the study of tissue diseases. Cryostats make it possible to section tissues or cells for examination.
- Molecular biology: Researchers can develop their knowledge of biochemical structures and processes by examining tissue sections.
- Immunohistochemistry: Immunohistochemistry is the process of identifying antigens in cells and tissues. The technique helps pathologists diagnose cancer.
- Semiconductor manufacturing: A semiconductor is a vital component of electronic devices. Advancing electronic components and devices depends on innovative techniques. One way scientists can explore quantum technologies and computing is by testing components and processes in a cryogenic environment like cryostats provide.
Types of Cryostats and Their Uses
Cryostats come in various designs, including semi-automated and fully automated models, each with its own advantages:
Closed-Cycle Cryostats
Closed-cycle cryostats use helium vapor and an external refrigerator that extracts, cools and recycles the helium exhaust vapors. The benefit of the cryostats is that they don't need to be refilled with helium and can run continuously as a result. However, closed-cycle cryostats need large amounts of electricity to operate.
Continuous-Flow Cryostats
These are floor-standing cryostats with an exterior vacuum chamber. Continuous-flow cryostats operate on a continuous flow of cooled liquid nitrogen or liquid hydrogen. They're ideal for research requiring a stable environment, as they have fewer associated vibrations than similar cooling systems.
Shop Used Cryostats at New Life Scientific
If you're looking to save costs while you grow your lab equipment, New Life Scientific can help. We provide quality used lab equipment that allows you to develop your setup while on a budget.
Woking with us eliminates the need to take unnecessary risks when purchasing used equipment. When you purchase from New Life Scientific, you have peace of mind knowing your equipment comes with a comprehensive warranty, and our experienced technicians complete testing and repairs.
Browse our available used cryostats or contact our helpful team for any further assistance.
