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 ring was then left on the ring finger. In a few European countries, the ring is worn on the left hand prior to marriage, then transferred to the right during the ceremony. For example, a Greek Orthodox bride wears the ring on the left hand prior to the ceremony, then moves it to the right hand after the wedding.