What is paraffin in rats? - briefly
Paraffin is a solid hydrocarbon wax employed to embed rat tissue specimens for histological analysis, providing a stable matrix that preserves morphology during sectioning. After infiltration, the wax solidifies, enabling the production of thin slices for microscopic examination.
What is paraffin in rats? - in detail
Paraffin wax is a petroleum‑derived, solid hydrocarbon employed as an embedding medium for rat tissue specimens. The material consists mainly of saturated alkanes with carbon chain lengths ranging from C20 to C40, providing a melting point between 55 °C and 60 °C. When heated above this temperature, the wax liquefies, allowing infiltration of fixed tissue blocks; upon cooling, it solidifies, forming a supportive matrix that preserves morphological detail during microtome sectioning.
The standard workflow includes fixation (commonly with 10 % neutral‑buffered formalin), dehydration through graded ethanol series, clearing with a solvent such as xylene, and infiltration with molten paraffin. Tissue blocks are then oriented in molds, covered with fresh wax, and allowed to harden. Sections of 4–6 µm thickness are cut on a rotary microtome, floated on a warm water bath, and mounted on glass slides for subsequent staining.
Key properties that make paraffin suitable for rat histology are:
- Low viscosity in the liquid state, enabling penetration of dense tissue.
- Chemical inertness, preventing reaction with most stains and antibodies.
- Transparency, facilitating microscopic examination after staining.
- Compatibility with a wide range of histochemical and immunohistochemical protocols.
Safety considerations include the use of organic solvents (e.g., xylene, isopropanol) during clearing and dehydration, which require proper ventilation and protective equipment. The wax itself is relatively non‑toxic but can cause skin irritation if handled while hot.
Alternative embedding media such as glycol methacrylate or optimal cutting temperature (OCT) compound are chosen when frozen sections or higher resolution are required. However, paraffin remains the preferred choice for routine morphological assessment, long‑term archiving, and large‑scale studies involving rat specimens.
Quality control measures involve monitoring the temperature of the embedding station, ensuring complete dehydration (residual water leads to tissue shrinkage), and confirming that the wax does not contain contaminants that could interfere with staining. Consistent preparation yields reproducible sections, essential for quantitative morphometric analyses and comparative pathology in rodent research.