Why do we use mice in research?


The popularity of mice in research stems from the fact that they are genetically very similar to humans. Biological processes in mice are also, to a certain degree, comparable to similar processes in humans. Mice are easy to keep, have a short generation time and can be produced in large numbers.

We keep mice until they are around eight weeks old before we allow them to breed to produce a next generation. The gestation period in this species is three weeks. After delivery, the pups stay with the mother for three to four weeks, after which they are weaned and housed in single sex groups to avoid unintended early pregnancies until they are old enough to produce a next generation themselves. 

Our colony management team collaborates with our researchers to ensure that our breeding programmes are scaled to the needs of our scientists' experiments. Members of the colony management team contributed to the NC3Rs best practice guidance on breeding and colony management.  

Our mice are housed in groups (two or more animals) per cage. At the Crick, the majority of mice are kept in individually ventilated cages. We do have mice that require more protection from the environment and are housed in groups in isolators. Individually ventilated cages are as the name says ventilated individually with sterile air. This keeps our animals protected from infectious agents that could cause disease.

We provide special pelleted diet in a food hopper per cage, and water through an automatic watering system. Each cage has its own water valve. Water and diet are provided without restriction, also called ad lib. A wood-based bedding is provided as well as nesting material. We also provide enrichment to each cage including cage balconies, and a selection of cardboard, and acrylic mouse houses, chewing blocks, and tubes.  

Most of the mice we use are genetically modified. Genetic modification of a gene or genes allows us to study their function and how they interact with other genes. Genetic modification also encompasses the introduction of a new gene, which is then called a transgene. Through genetic modification, mice become models for human traits and diseases that have a genetic predisposition for example as result a result of a genetic mutation. 

Mice are being used in a wide range of research programmes in the Crick, including