The funding for these experiments are through NASA grants. This is where the Research Opportunities link will take you. It seems like microgravity would pose a problem. Waste products are certainly more difficult to deal with without gravity holding them to the desk top or floor. Therefore, we must use forced air circulation systems.
Mice introduce more problems since their urine has a very strong odor.
Typically, we will fly rats in place of mice. One of the most important things David does is make sure that experiments never jeopardize the health and safety of the space shuttle crewmembers. The primary safety concerns for biological experiments involve on of the ways in which we preserve the biological tissue. You noticed that the frogs looked alive, felt real, yet they were completely dead. Formaldehyde is a type of fixative that terminates the cellular growth without damaging the tissue.