Human post-implantation embryo collection: medical and surgical techniques.

Knowledge of the genetic control of early human development is limited with most information being extrapolated from studies in animal models. There is compelling evidence that undertaking gene expression studies in human embryos can be expected to dramatically enhance our understanding of embryonic formation and malformation. Such studies require the systematic and coordinated collection, storage and study of human embryos. We have successfully collected intact embryos from cases undergoing termination of pregnancy (TOP). Embryonic material was collected from 62% of attempts using a technique of surgical aspiration carried out under ultrasound guidance. Collection rates were lower after medical termination of pregnancy (41%) although the proportion of undisrupted embryos was identical with the two methods (26%). Surgical aspiration provided intact embryos between Carnegie stages (CS) 16-22 while earlier developmental stages were collected from medical terminations. Our collection of over 60 intact specimens, spanning Carnegie stages 10 to 22 (about 21 to 53 days of development) covers a huge window of critical developmental events and hence represents an exciting and valuable research resource.