How should a mouse be properly defrosted? - briefly
The mouse must be defrosted in a sealed, leak‑proof bag placed in cold water, with the water replaced every 30 minutes until fully thawed. For a slower method, keep the sealed package in a refrigerator at ≤ 40 °F (4 °C) for 12–24 hours.
How should a mouse be properly defrosted? - in detail
When a frozen laboratory mouse must be returned to a viable state, follow a controlled, temperature‑regulated protocol to minimize tissue damage and preserve physiological integrity.
The process begins with preparation of a thawing environment:
- Set a water bath to a temperature between 20 °C and 25 °C. Avoid temperatures above 30 °C, which can cause rapid thermal shock.
- Fill the bath with sterile, isotonic saline solution (0.9 % NaCl). The solution maintains osmotic balance and reduces cellular dehydration.
Thawing steps:
- Remove the animal from cryogenic storage, handling it with insulated gloves to prevent accidental warming.
- Place the sealed container directly into the pre‑warmed saline bath. Ensure the container remains closed to prevent contamination.
- Monitor the internal temperature using a calibrated thermocouple inserted through a sealed port. Aim for a gradual increase of 1 °C–2 °C per minute.
- When the core temperature reaches 4 °C, transfer the mouse to a secondary bath set at 37 °C for a brief equilibration period of 5–10 minutes. This step restores normal physiological temperature without abrupt changes.
- After reaching 37 °C, gently dry the exterior with sterile gauze and place the mouse in a recovery cage with warmed bedding and access to water.
Post‑thaw assessment:
- Observe respiration rate and muscle tone for at least 30 minutes. Absence of spontaneous breathing or severe tremors indicates the need for immediate veterinary intervention.
- Record body weight and temperature to verify stability before proceeding with experimental procedures.
Key considerations:
- Maintain sterility throughout; any breach can introduce pathogens.
- Document all temperature readings and time intervals for reproducibility.
- Do not employ microwave or direct heat sources; uneven heating compromises cellular membranes.
Adhering to this systematic approach ensures that the thawed mouse retains functional viability and reduces the risk of experimental variability.