About Fat Cells
Adipose tissue is found in specific locations, which are referred to as 'adipose depots.' Adipose tissue contains several cell types, with the highest percentage of cells being adipocytes, which contain fat droplets. Other cell types are also found though, which include fibroblasts, macrophages and endothelial cells.(and several other types)
Actually, this is the only reason, why we are interested in "fat-cells", but maybe this was clear to you from the beginning of starting to read this note, since "fat" happens to be "the richest source of regenerative cells in the body".