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In life science research, pharmacology and toxicology experiments, and pathological diagnostics, the animal dissection and tissue sampling room serves as the critical bridge between in-vivo experimentation and downstream data analysis. The design standards of this space, the rigor of operational procedures, and the effectiveness of biosafety controls directly determine the integrity of experimental samples and the reliability of research data.

This article analyzes the key technical considerations of modern animal dissection and sampling laboratories from three perspectives: facility configuration, standardized operating procedures, and biosafety control.

I. Core Functional Configuration of a Dissection and Sampling Room

A professional animal dissection and sampling room must support the entire workflow—from euthanasia and organ exposure to tissue fixation and waste disposal. According to current laboratory construction standards, the main configurations include the following two aspects:

1. Infrastructure and Work Platforms

Dissection procedures should be performed on dedicated dissection tables or negative-pressure ventilated necropsy tables. For small and medium laboratory animals (such as mice and rabbits), negative-pressure ventilated necropsy tables have become the standard configuration.

These systems use negative pressure exhaust and gas treatment units to effectively remove organic gases and odors such as formaldehyde and methyl mercaptan generated during dissection, protecting operators from exposure to harmful aerosols.

The work surface should also be equipped with:

• Anesthetic gas exhaust interface

• Localized lighting system

• Instrument sterilization tray

2. Sampling and Waste Disposal Equipment

Instrument Preparation

Common dissection instruments include:

• Animal fixation board

• Surgical scissors of different sizes (ophthalmic scissors, tissue scissors)

• Surgical blades

• Toothed and non-toothed forceps

• Hemostatic forceps

• Bone cutters

• Measuring ruler and electronic balance for organ measurement

Waste Management

According to the Laboratory Animal Biosafety Regulations, the dissection area must be equipped with:

• Yellow biohazard waste bags for animal carcasses and organs

• Sharps containers for used needles and blades

These materials must never be mixed with regular household waste.

II. Standardized Dissection and Tissue Sampling Procedures

To improve experimental reproducibility and minimize artifacts caused by improper handling, dissection and tissue sampling must follow strict technical protocols.

1. Preoperative Preparation and Animal Handling

Animal anesthesia or euthanasia must be completed rapidly to avoid prolonged stress responses. Excessive stress may alter enzyme activity within tissues, potentially leading to autolysis, which can affect the accuracy of light microscopy or electron microscopy observations.

External Examination

Before dissection, the animal's body surface should be systematically examined, including:

• Natural openings (mouth, nose, anus) for abnormal secretions

• Hair condition and glossiness

• Presence of trauma, swelling, or lesions

These observations often reflect the physiological or pathological condition prior to death.

2. Tissue Exposure and Organ Observation

Dissection Approach

Animals are typically fixed in the supine position, and the abdominal and thoracic cavities are opened along the midline incision.

The following observations should be recorded:

• Presence of fluid, blood, or adhesions in the cavities

• Size, color, and texture of organs

• Visible lesions or abnormalities

Lesion Documentation

For model animals with specific pathological features (such as tumors or necrotic areas), lesions should be described objectively, including:

• Location

• Shape

• Color

• Size (accurate to millimeters)

• Relationship to surrounding tissues

3. Technical Specifications for Tissue Sampling

Correct sampling procedures are critical to specimen quality. The following technical principles must be followed:

Speed and Temperature Control

After removal, tissues should be immediately immersed in pre-cooled fixative (usually 4°C).

Prolonged exposure at room temperature may lead to the release of intracellular hydrolytic enzymes, which can damage cellular ultrastructure.

When necessary, cutting operations may be performed on ice packs or chilled trays.

Sample Size Requirements

• Electron microscopy specimens: usually not larger than 1 mm³ due to the slow penetration of fixatives.

• Routine paraffin sections: tissue thickness should be 3–5 mm, with a recommended size of 1.5 cm × 1.5 cm.

Instrument Usage Standards

• Cutting must be performed with sharp blades.

• Pulling, sawing, or compressing with dull instruments must be avoided to prevent mechanical damage.

• When holding tissue, non-toothed forceps should grasp surrounding connective tissue rather than the target tissue itself to prevent cellular deformation.

III. Standard Sampling Sites for Key Organs

To ensure comparability between experiments, sampling locations for the same organs must remain consistent. According to laboratory guidelines issued by institutions such as RWD Life Science and Meifengli, standard sampling practices include:

• Brain: transverse sections from the forebrain (frontal lobe), midbrain (parietal lobe), and cerebellum. Specific sampling points are required for hippocampal observation.

• Heart: longitudinal incision from the auricle to the apex to expose the right atrium, atrioventricular valves, right ventricle, and left ventricular wall.

• Liver: select both the largest lobe (e.g., left lobe) and smallest lobe (e.g., caudate lobe). Tissue should be sampled 5 mm from the edge, including capsule and parenchyma.

• Kidney:

  • Left kidney: transverse section through the hilum to expose pelvis, cortex, and medulla.

  • Right kidney: longitudinal section including the hilum.

• Digestive tract:

  • Stomach: sample along the greater curvature from cardia to pylorus.

  • Intestine: sections from duodenum, jejunum (including Peyer’s patches), ileum, and colon. Contents should be removed and tissues flattened on filter paper before fixation to prevent curling.

IV. Biosafety and Waste Management

For dissections involving highly pathogenic microorganisms (e.g., infected non-human primate models), procedures must be conducted in high-level biosafety laboratories.

According to the Animal Dissection Biosafety Technical Guidelines, the following control measures should be implemented:

1. Personnel Protection

Operators must wear:

• N95 or higher-level respirators

• Face shields

• Double gloves

• Waterproof isolation gowns

These protective measures help prevent infection caused by body fluid splashes or aerosol exposure.

2. Environmental Control

Dissections should be performed in a negative-pressure environment, where airflow passes through HEPA filtration systems before discharge.

3. Carcass Disposal

After experiments:

• Animal carcasses and contaminated materials must be autoclaved or stored in designated low-temperature medical waste freezers.

• Final disposal should be conducted by licensed medical waste treatment agencies through incineration.

V. Selection and Application of Fixatives

Fixation is the critical step following tissue sampling, aimed at stabilizing cellular structures and preventing enzymatic degradation and decomposition.

Different research purposes require different fixatives:

Important Notes

• The volume of fixative should be 10–50 times the tissue volume.

• Typical fixation time ranges from 24–72 hours.

• For organs containing air (such as lungs), fixative should be injected to inflate the tissue, ensuring full contact with the solution.

Conclusion

An animal dissection and tissue sampling room is not merely a physical surgical space but a comprehensive technical platform integrating biosafety control, standardized operating procedures (SOPs), and precise specimen preparation.

Strict adherence to sampling protocols, the use of professional negative-pressure dissection equipment, and compliance with biosafety regulations are essential to:

• Ensure the accuracy and reproducibility of scientific data

• Improve laboratory biosafety management

• Enhance the overall quality of experimental research.