The chemical composition of human and mouse adipose tissue taken from fat and thin individuals has been determined.The tissues were obtained from the epididymal fat pads of fat, lean and normal strains of mice and from sixty-one human subjects undergoing various abdominal operations. In both the mice and the humans, the adipose tissue from obese individuals contained slightly more fat and less protein and water than that from lean individuals. However, the differences were small and it is concluded that obese individuals containi, in their total adipose tissue, much more non-fatty cellular material than do the lean.

Leptin is expressed in the placenta and in certain fetal tissues; however, little is known with regard to the function of this hormone in these tissues. To date, most evidence suggests that placental and/or fetal leptin acts as a fetal growth factor, but this is far from clear. Leptin may also have physiological effects on the placenta, including angiogenesis, growth and immunomodulation. The effects of placental leptin, if any, on the mother may contribute to endocrine-mediated alterations in energy balance, such as the mobilization of maternal fat, which occurs during the second half of pregnancy. In this review we will address these and other issues related to the expression of both placental and fetal leptin.