Objective: To assess the prevalence and etiology of the empty follicle syndrome (EFS).Design: Observational longitudinal study.Setting: Tertiary fertility centers.Patient(s): All patients beginning in vitro fertilization (IVF) treatment from December 2002 to November 2004 were included. Couples undergoing IVF with donor oocytes or participating in an experimental IVF study were excluded from analysis.Intervention(s): Identification of EFS cycles. Comparing ovarian hyperstimulation strategy, follicle count, and timing of human chorionic gonadotropin (hCG) for final oocyte maturation of the EFS cycles with normal IVF cycles.Main Outcome Measure(s): Number of follicles punctured, number of oocytes recovered, previous and future IVF attempts, and serum hormone levels.Result(s): Twenty-five of a total of 1,849 patients were identified with an EFS cycle. Reasons for occurrence of EFS cycles were mistiming of hCG for final oocyte maturation, premature ovulation, and poor ovarian response. None of the affected patients had experienced EFS cycles in earlier IVF attempts nor were there any recurrence in subsequent treatments.Conclusion(s): Accurate timing of induction of final oocyte maturation, properly scheduled ovarian hyperstimulation, instruction of patients and doctors, and full workup for IVF are essential for the successful recovery of oocytes. Occurrence of EFS in IVF can normally be attributed to a failure of at least one of these factors and probably rarely or never occurs otherwise.

Cell transplantation is being discussed as a potential therapy for multiple disorders caused by loss or malfunction of single or at most a few cell types. These include diabetes, Parkinson's disease and myocardial infarction or cardiac failure. However, it is not yet clear whether cells from adult tissues ('adult stem cells') or embryos ('embryonic stem cells') will prove to be the most appropriate replacement cells; most likely, each disease will have its own preferred source. This study presents the background to this discussion and the current state of research in replacement of cardiac tissue, with focus on recent developments using human embryonic stem cells. It also describes a new human embryonic stem cell (HESC) line, NL-HESC1, the first to be derived in the Netherlands, and shows that it forms cardiac cells in a manner comparable with that of hES2 and hES3 cells grown in the same laboratory.