Abstract: The invention provides novel methods by which adipose tissue, preadipocytes, and adipocytes can be generated for research purposes, and methods for identifying cell populations that can proliferate and differentiate into adipocytes in vivo. The invention further provides a means for the in vivo derivation of “designer” or “customized” adipose tissue, preadipocytes, and adipocytes. Also provided are methods for identifying agents that affect adipocytes and adipose tissue, as well as the agents themselves. In particular, the present invention allows for creation of tissues and cells that can be used to screen for agents useful for treating human disorders associated with adipose tissue, including obesity, metabolic syndrome, and diabetes.