Brown adipose tissue is present in small mammals (e.g., mice) and in newborn humans. Most of it disappears in adult humans. The cells in both types of fat are called adipocytes although they differ in origin, structure, and function in the two types of tissue.
On the left hand, index finger. It's not the index finger you wear it on. Left hand, ring finger. The finger that you would wear a wedding ring on.
The wedding finger is the same as the ring finger, the finger next to your pinky on your left hand. They are the same for both guys and girls. In the United States and other English-speaking nations, it's the finger between the middle and pinky finger on the left hand. That finger is called the ring finger.