The latest volume on trophoblast research from URP contains papers on the following themes: Placental Permeability and Transport - examines the role of the placenta in maintaining the development of the conceptus; Placental Metabolism -explores how the placenta metabolizes amino acids and other nutrients; Fetal-Placental Circulation -<196 explores the controlling factors which modulate the blood flow in the fetal-placental circulation; Implantation, Differentiation and Invasion -examines the interaction of the blastocyst/trophoblast with the endometrium and the control of trophoblast invasion and differentiation.