There are multiple mouse species that are used in research labs, ranging in size shape and genetic composition. You have the widely used Black-6, which is fairly common and ordinary. But then, you have specimens that range from strange to downright horrifying. Has science gone too far? Well, you be the judge:

  1. The nude mouse

Believe it or not, the fact that it is hairless is not the most interesting thing about this mouse. The genetic modification that makes it lose all its hair also greatly weakens its immune system. This is done in order for its body to not reject foreign tissue grafts from different species. The foreign tissue in a research setting could be human tumors for example, and cancer researchers will be able to try out different treatments to destroy them.

  1. The ear mouse

So you have a mouse that can accept foreign tissue and care for it as if it were its own, what’s next? Well, Dr. Charles Vacanti created a biodegradable scaffold and seeded it with cartilage cells taken from a cow. He then implanted this scaffolding on the back of a nude mouse, whose blood nourished the cells and dissolved the scaffolding. The result – a perfect replica of a human ear. Mind you, this was back in 1997. The ear was never used, because the human immune system would reject it, but Dr. Vacanti would use a similar technique in order to grow a chest plate for a 16-year-old boy.

  1. The almost nude mouse

One area of research is baldness in men, and to this effect, Japanese researchers have taken the nude mouse and successfully managed to make it grow hair by implanting mouse or human stem cells into its skin. The hair follicles of the mouse even connected to muscle and nerves in order to make the hair stand on its ends.

  1. The morbidly obese mouse

Obesity and diabetes are major, chronic problems that affect the lives of millions of people, and who better to help us solve these problems than mice. The morbidly obese mouse goes all the way back to the summer of 1949, when researchers managed to breed mice with two defunct copies of the ob gene that regulates foot consumption. So these mice will eat and eat and eat until they turn into furry balloons. The best part? The Jackson Laboratory in the US breeds these mice by the millions.

  1. The human-sphincter mouse

If you thought you’ve seen weird, well get ready, because there is a mouse that has a human sphincter. The human sphincter can stop functioning due to injury, as is the case in certain situations during childbirth. Researchers managed to build a sphincter that was made out of human muscle cells and mouse nerves under the skin of a lab mouse, and this research helped make strides into surgery that can restore function to a damaged sphincter.