Wait, we didn't mean McDonald's will some day include Mickey Mouse Burgers on their menu.  But in the future, cows and maybe even elephants will come from mice. At present, scientists have successfully produced healthy baby rats from rat sperm cells grown in mouse testicles.  

Takashi Shinohara, a molecular geneticist at Kyoto University in Japan, and his colleagues developed the technique called in-vitro microinsemination. This breakthrough proves it's possible to store functional sperm cells of bigger animals in small "packages" such as mice.

Although it sounds like these scientists have too much time on their hands, the new technology could prove very useful in farming and agriculture. Cattle farmers could save space and food by growing bull sperm in mice.
 
The technique could also be used in conserving endangered animals using frozen sperm stem cells. Sperm stem cells, which give rise to cells that develop into sperm, can be transplanted into mouse testicles to produce viable sperm.