Efficient method for preparing pseudopregnant mice promotes laboratory animal welfare

In biomedical research using mouse models, preparing pseudopregnant recipient females is a standard step in embryo transfer protocols. Conventionally, this process requires technicians to select female mice showing clear signs of estrus. Because only a limited percentage of mice naturally enter this stage daily, facilities often maintain a relatively large stock of female mice. Furthermore, group housing can induce the "Lee-Boot effect," a biological phenomenon in which caged females suppress one another's estrous cycles, decreasing selection efficiency and requiring careful management to ensure animal well-being.