This revised sixth edition has been updated to reflect recent advances in developmental and molecular biology and embyrology. Every chapter has been revised to reflect new findings in research and their clinical implications. Advances in developmental biology affecting knowledge about the cause of birth defects and prenatal management of foetuses are integrated into the clinically oriented book. MR and ultrasonographic images should help the reader to understand developmental processes, and how to detect foetal defects by amniocentesis, chorionic villus sampling, and ultrasonography.