Mini Mouse

I read recently about the ability to engineer a certain type of mouse in the lab by crossbreeding two mice of differing developmental growth deficiencies. While trying to find more information on the subject, however, I stumbled upon the naturally occurring African Pygmy Mouse, which is of similar size and variety.

The mini-mouse is achieved by parenting a mouse with a defective growth-hormone receptor gene with a mouse with defective IGF gene. The mouse lacking the growth-hormone receptors is only about half the size of a normal lab mouse, whereas the mouse with deficient IGF is only about a third of the size. The product of this dominant gene deficient union is lacking in both and end up weighing around 5grams fully grown.

This is incredible small for a mammal. A dime weighs 2 grams. So stack up 2 to 3 dimes and you'll have the equivalent weight of a living mammal in your hands. IInterestingly this is the same size as the naturally occurring pygmy mouse. I do not yet know if they are a result of similar deficiencies, but I would have to assume otherwise at this point since they make up an entire species. The differences in biology between these two tiny rodents could be uite revealing.