How to preserve a mouse animal? - briefly
After humane euthanasia, immerse the specimen in 10 % neutral‑buffered formaldehyde for 24‑48 hours, then move it to 70 % ethanol and store at 4 °C. For molecular work, snap‑freeze in liquid nitrogen and keep at –80 °C.
How to preserve a mouse animal? - in detail
Preserving a mouse specimen requires a clear plan that matches the intended downstream analysis. Choose a fixation method that maintains the structures of interest. For histological examination, immerse the animal in 10 % neutral‑buffered formalin for 24–48 hours at room temperature; ensure complete penetration by submerging the whole body or dissected organs. For immunohistochemistry, replace formalin with 4 % paraformaldehyde in phosphate‑buffered saline and keep the tissue at 4 °C to limit antigen degradation.
If molecular integrity is the priority, avoid cross‑linking chemicals. Snap‑freeze the mouse in liquid nitrogen within minutes of euthanasia, then store the whole carcass or dissected tissues at –80 °C. For RNA preservation, transfer samples immediately into an RNA‑stabilizing solution such as RNAlater and keep at 4 °C for up to 24 hours before moving to –20 °C or –80 °C.
When long‑term storage is required, embed fixed tissue in paraffin or resin. Follow these steps:
- Dehydrate through graded ethanol (70 % → 100 %).
- Clear with xylene or a xylene substitute.
- Infiltrate with molten paraffin (58–60 °C) and allow solidification.
- Cut sections on a microtome and mount on slides; store slides in a desiccated environment.
For cryopreservation, embed tissue in optimal cutting temperature (OCT) compound, freeze on dry ice, and keep at –80 °C. Sections can be cut on a cryostat and stored at –20 °C in airtight containers.
Maintain a detailed log that records:
- Date and time of euthanasia.
- Fixative type, concentration, and volume.
- Temperature and duration of each processing step.
- Storage conditions and location of each sample.
Ethical compliance demands that euthanasia follow approved protocols, that fixation agents are handled with proper protective equipment, and that waste disposal conforms to institutional regulations.
By adhering to these precise procedures, a mouse specimen remains suitable for morphological, immunological, or molecular investigations over extended periods.