The appearance of an individual mouse may vary according to the size of its species. However, the bodies of all mice include lungs, reproductive organs and kidneys, as well as the spleen, brain, spinal cord, heart, liver, stomach, diaphragm, urinary bladder, thorax, small intestine, large intestine and gall bladder.
Mice are commonly used in laboratory settings as test subjects. Some are even bred specifically for laboratory use. The physiology of the mouse is similar to that of most mammals, humans included. Their body parts also respond to stimuli in much the same way that human body parts respond. Great advances have been made in science and medicine as a result of mice. In fact, almost all medicines approved for human use have been tested first on lab mice.