How Does a Cryostat Work?
The cryostat operates by maintaining a chamber at sub-zero temperatures, typically between -20°C to -30°C. Tissue samples are embedded in a medium like
Optimal Cutting Temperature (OCT) compound, which provides support during sectioning. A microtome within the cryostat then slices the tissue into thin sections, usually around 5-10 micrometers thick. These sections are then mounted on slides for further staining and examination.
Rapid Diagnosis: In clinical settings, cryostats enable quick preparation of tissue sections, allowing for immediate examination and diagnosis.
Preservation of Antigens: The freezing process preserves the native state of antigens, making cryostat sections ideal for immunohistochemical staining.
Minimal Chemical Alteration: Unlike paraffin-embedded sections, cryostat sections are not exposed to harsh chemicals, preserving the tissue's biochemical integrity.
Sample Preparation: The tissue sample is first embedded in OCT compound.
Freezing: The embedded sample is rapidly frozen in the cryostat chamber.
Sectioning: The microtome slices the frozen tissue into thin sections.
Mounting: The sections are placed onto glass slides.
Staining: The sections are stained using appropriate dyes or antibodies for microscopic examination.
Advantages of Using Cryostat
There are several advantages to using cryostat in histological studies:Limitations and Challenges
Despite its advantages, cryostat sectioning has some limitations: Tissue Integrity: Some tissues, especially fatty tissues, are challenging to cut consistently.
Thickness Limitations: Cryostat sections are usually thicker compared to those obtained by paraffin embedding.
Handling and Storage: Frozen sections require special handling and storage conditions to prevent degradation.
Applications in Research and Medicine
Cryostat sections are widely used in various fields: Clinical Diagnosis: For rapid intraoperative diagnoses to guide surgical decisions.
Research Studies: For studying the distribution of proteins, nucleic acids, and other molecules within tissues.
Teaching: As an educational tool for medical and biological sciences.
Conclusion
The cryostat is an invaluable tool in histology, offering rapid and efficient preparation of tissue sections with minimal chemical alteration. While there are certain challenges, its advantages make it indispensable for both clinical and research applications.
