Angiogenesis and implantation

Mammalian implantation is a complex, but still poorly understood, process i n which the developing embryo establishes contact with the endometrial surf ace epithelium before developing a haemochorial placenta. The growth and de velopment of the placenta and its subsequent invasion into the decidua can be likened to the invasion of healthy tissue by malignancy. The establishme nt of an angiogenic phenotype is a critical event in the progression of ben ign disease to malignant. Little is known about the role of angiogenesis in implantation but in view of the importance of vascular development to the receptive endometrium, angiogenesis is likely to be critical for successful implantation. Here, the factors that control the development of blood vess els in the pre-implantation phase are reviewed and the complex interplay be tween the embryo and decidua that leads to the establishment of a healthy p lacenta is considered.