The "ear" was grown on the mouses back because it's a good idea to have a "spare" human ear. The ear is very difficult to repair and is often damaged in car accidents, fights, fires, and also a disease called microtia; meaning "little ear" which can result in a slightly smaller ear or almost no ear. Also because it is mostly made of cartilage, which is hard to work with and the ear has a complicated shape that is highly visable.
The proper start to growing a human ear on a mouse's back is to first cut off a human ear. As highly qualified doctors, we would highly recommend you shave the rat beforehand for best quality hearing. Next, you are going to dip the ear in a pool of ear cells to make sure the ear functions properly on the rat's back. After, you are going to super glue and duct tape on to the rat's back and the rat's DNA should immediately respond to the new cells and work superbly.
Usually when a mouse ear gets crusty its because it has an ear infection or a tick (flea)
go to the vet and get the ear stiched.
The number varies by about seventeen.
A human ear
snake
mites
You should have had it done by an professional body piercer, not some clown in the mall, go see your doctor.
The receptors in the ear detect a vibration, so impulses are sent to the brain. Then the brain makes the response and impulses are sent along the neurones back to the receptor to create the mouse to jump.
About six inches.
stirrup
When they are grown up and when they are over 4inches.