Developmental biology: Neither fat nor flesh (Brown and white fat)

Brown and white fat

In mammals, white adipose tissue stores fat, whereas brown adipose
tissue burns fat. Brown adipocytes have a common origin with muscle
cells, which could help explain their unusual function.
http://www.nature.com/nature/journal/v454/n7207/full/454947a.html

http://www.cell.com/retrieve/pii/S0092867408010635