This book provides a unique, up-to-date overview of recent research on avian ovarian follicles and ensuing early embryonic development after fertilization. The transition between these two domains forms a large gap in our knowledge about the involved developmental processes.The publication compiles data gained over a period of 40 years from in vivo and in vitro culturing of quail and chicken eggs and blastoderms. By countless photographs and diagrams, insight is gained into many morphological, ultra-structural, histological and biochemical structures in different ooplasms, seen both before and after fertilization. The book culminates into a brand-new ‘embryo in box’ model, distilled from examination of the fate of the four ooplasms in the avian blastoderm and neighboring ooplasm, the events in the extrablastodermal subgerminal ooplasm and subgerminal space at the moment of laying, as well as the inductive influences of tissues with nonembryonic fateon the upper layer from which the whole embryo proper forms, resulting in the formation of a primitive streak and Hensen’s node.MARC CALLEBAUT is Emeritus Professor of Human Anatomy and Embryology at the Faculty of Medicine and Health Sciences (Dep. ASTARC) of the University of Antwerp (Belgium). He taught Human Anatomy and Embryology to medical students and has published approximately 150 papers in the eld of oogenesis, folliculogenesis and early embryonic development.