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Cryostat is a sectioning instrument which maintains low-temperature conditions for the tissues to reach a certain level of hardness by rapid freezing. Then, it is used for cutting the sample in slides within a certain thickness range, preparing the tissue samples for other relevant operations. It is applicable to the sectioning of fresh tissue samples, including animals, plants and human body tissues.
The cryostat temperature range: chamber temperature: -18~20℃; specimen head temperature: -15~-20℃. Breast adipose tissue is the hardest one to handle among all the sample sectioning. The chamber temperature has to be set at its minimum and the specimen head temperature has to be adjusted to -50℃. The section thickness could be set at 10μm -15μm.
Frozen section thickness range: 5μm ~20μm. 6-8μm for clinical applications. 5μm works best for lymph nodes as their cells are denser. For scientific research, section thickness is commonly set at 8μm, -10μm or 20μm.
After setting up the optimal temperature for sectioning, a tissue sample of standard size should be embedded with the optimal cutting compound on the sample plate. Then, It should be embedded with the optimal cutting compound on the sample plate. Upon the completion of embedding, mount the sample on the specimen head and use the sample injection method to obtain frozen sections.
Cryostats are widely used in domains such as histology, pathology, cytology, neurology and so on, including instant clinical diagnosis; enzyme histochemistry research and diagnosis; immunofluorescence technique, immunohistochemistry technique, in situ hybridization technique; non-enzyme substance identification and research; neuropathology research; spatial transcriptomics sectioning.
The most common types of frozen sectioning machines are semi-automated and fully automated cryostats.
The semi-automated cryostat possesses a cryochamber and a specimen head for separate freezing. Both are engineered with motorized sample injection and UVC disinfection. For seasoned technicians, a semi-automated cryostat is the first choice for higher sectioning efficiency.
The fully automated cryostat does not only possess the features of the semi-automated one, it also has a cut window function that allows the setting of the size of the section to prevent any subsequent disruption caused by the OCT; Meanwhile, it has an automated sectioning feature, allowing newbies to carry out day-to-day cryosectioning smoothly.
| Strengths | Weaknesses |
1. It’s convenient. The tissue does not need fixation, dehydration, clearing and embedding before sectioning. 2. It’s fast and time-saving. 3. It doesn’t induce great changes in the tissue. 4. fats and lipids components can be well preserved. 5. It can preserve the antibody activities and enzymes better, especially the surface antigens and water-soluble enzymes which are less heat resistant and less tolerant to organic solvents. | 1. It’s difficult to prepare serial cuts. 2. The size of the tissues cannot be too large for sectioning. (1.15×1.15×0.12~0.13cm in general). Otherwise, it is difficult to freeze the whole section or it might result in inconsistent freezing, undermining the section results and the effects of staining. 3. It is difficult to prepare thinner slides. 4. Ice crystals are formed during the freezing of tissue blocks, affecting the cellular structure and the position of the antigenic substances. Also, the structure of the tissues is not clearly shown as that in paraffin sectioning. |
A cryostat machine usually encompasses the cooling, sectioning, safety and operation system.
Refrigeration System
Cryochamber and specimen head carry out cooling separately. For the cryochamber, a compressor is used for cooling. As temperature difference arises during sectioning, the compressor provides double compensation for temperature loss to maintain the cryochamber temperature and ensure the quality of the section results. As for the specimen head, a low-pressure refrigeration system and semi-conducting elements are adopted for cooling, offering faster temperature control. The specimen head temperature can switch between -20℃~-50℃ within one minute. Technicians don’t have to wait anymore to start their work.
Frozen Sectioning System
The highly calibrated cross-roller bearings are equipped with a highly-dense spindle. The high-resolution sampling motor and horizontal sampling slide made of aviation aluminium render a highly-precise injection system, meeting the 0.5μm sample injection requirements. As such, the accuracy of sectioning can be preserved. A highly accurate coder and electric brake ensure smooth sectioning.
Safety System
The low-temperature UV disinfection system can operate at any time and at any temperature. It effectively kills infectious tissues, bacteria and viruses. The waste liquid management system sends out a warning when the current waste bottle is not in a position or the waste liquid overflows. This prevents the waste liquid from flowing out and causing contamination to the ground so as to protect the laboratory staff and uplift the quality control and management standard of the laboratory.
Operation System
Specimen head orientation is visible during adjustment that offers an effective solution to the time-consuming and energy-draining process of adjusting the specimen head. The convenience therein allows fast re-orientation, thus avoiding the waste of samples. It has an auto switch for sleep mode or wake-up mode, saving a lot of valuable time for scientific research.
The operation record is traceable, rendering centralised equipment management convenient. As a result, troubleshooting is fast and easy that guarantees smoothness at the very beginning of the project (without this function, troubleshooting will be time-consuming that might hinder the start of the operation in the laboratory); it also cuts down maintenance costs effectively.
Read more: https://www.rwdstco.com/detailed-explanation-of-11-key-problems-of-cryostat/
For Technicians
The cryostat machine is mainly used in pathological diagnosis during surgery. Its prominent features are fast sectioning performance and fast delivery of section results. Therefore, given that the technicians have such expectations for a cryostat, there are four points for them to consider when choosing a cryostat.
(1) Double cooling/refrigeration design: cryochamber and specimen head carry out freezing separately to ensure that the tissues are kept at the best temperature for sectioning and enhance the efficiency and quality of the sectioning performance.
(2) Temperature stability: Sectioning done with an open window might induce temperature crossover both internally and externally, creating a large temperature difference in the cryochamber that undermines the sectioning performance. At this point, a machine has to be employed for solving this problem through relevant technologies.
(3) Precision of sectioning: Frozen sections are thicker than other types of sections in nature. Some research results are affected by section thickness. If the accuracy of sectioning cannot be guaranteed, the thickness of section results will deviate even further from the preset thickness.
(4) Operation and stability: The design of functions is simple and clear. It provides an easy way to get started with sectioning. Meanwhile, it has to be highly stable to ensure the consistency of working performance and maintain durability.
For Amateurs
(5) Choose a well-known brand because of its cutting-edges of quality and stability. RWD cryostat displays a short service response time and offers a comprehensive user service network. Its user landscape covers over 100 regions around the world. Meanwhile, choose the most suitable brand and model based on the actual needs of the laboratory. Don’t blindly pursue high-end instruments or inexpensive equipment.
(6) If conditions allow, the best practice is to invite a professional technician to test the product on spot. This could greatly reduce the chances of buying substandard products.
(7) Study the user service coverage and other details of the manufacturer of that brand. Check whether it provides sufficient training services, technical support and aftersales service support.
(8) The last point is about passing the quality acceptance. Does the brand offer information for checking and acceptance based on the laboratory’s requirements during the agreed delivery time?
