High-Yield embryology

Abstract

The fifth edition of High-Yield™ Embryology includes improvements based on suggestions and comments from the many medical students who have used this book in preparation for the USMLE Step 1 examination and those students who have reviewed the book. I pay close attention to these suggestions and comments in order to improve the quality of this book. The goal of High-Yield™ Embryology is to provide an accurate and quick review of important clinical aspects of embryology for the future physician. Many times in the history of science, certain biological concepts become entrenched and accepted as dogma even though recent evidence comes to light to challenge these concepts. One of these concepts is the process of twinning. Recent evidence calls into question the standard figures used in textbooks on how the process of twinning occurs. In particular, it is becoming increasingly difficult to ignore the fact that dizygotic twins are sometimes monochorionic.