What are Tissue Sections?
Tissue sections are thin slices of biological tissues that are prepared for examination under a microscope. These sections are crucial in the field of
histology, which is the study of the microscopic structure of tissues.
Why are Tissue Sections Important?
Tissue sections allow researchers and medical professionals to observe the detailed structure and organization of cells and
tissues. This examination can help in diagnosing diseases, understanding normal physiological processes, and conducting
research in various biological sciences.
Fixation: This step preserves the tissue's structure by using chemical fixatives like
formaldehyde or glutaraldehyde.
Embedding: The fixed tissue is embedded in a medium like paraffin wax or resin to provide support during sectioning.
Sectioning: The embedded tissue is cut into thin sections using a microtome or an ultramicrotome. Sections are typically 3-5 micrometers thick for light microscopy and 50-100 nanometers thick for
electron microscopy.
Staining: Staining enhances the contrast of the tissue sections, making specific structures more visible under the microscope. Common stains include
Hematoxylin and Eosin (H&E), which provide a general overview, and specialized stains like
Masson's Trichrome for connective tissues.
Light Microscopy: Uses visible light to illuminate the tissue sections, suitable for general histological studies.
Fluorescence Microscopy: Uses fluorescent dyes to label specific cellular components, providing more detailed information.
Electron Microscopy: Uses electron beams to achieve much higher resolution, suitable for ultrastructural studies.
Cellular Components: Nucleus, cytoplasm, and organelles like mitochondria and the endoplasmic reticulum.
Tissue Organization: Arrangement of cells in different
tissue types like epithelial, connective, muscle, and nervous tissues.
Pathological Changes: Abnormalities such as cancerous cells, inflammation, or tissue damage.
Artefacts: These are distortions or anomalies introduced during preparation, like folds, tears, or bubbles.
Thickness: Achieving the right thickness is crucial for optimal visualization; too thick or too thin sections can obscure details.
Staining Variability: Inconsistent staining can lead to misinterpretation of the tissue structures.
How are Tissue Sections Stored?
Tissue sections are typically mounted on glass slides and covered with a protective coverslip. They can be stored long-term in slide boxes or cabinets at room temperature. For prolonged preservation, especially for immunohistochemistry, sections may be stored at 4°C or even -20°C.
Future Directions in Tissue Sectioning
Advancements in
technology and techniques continue to improve tissue sectioning. Innovations such as
automated microtomes, advanced staining protocols, and digital pathology are making the process more efficient and accurate. These advancements are expected to further enhance our understanding of tissue biology and disease mechanisms.
