The origin of the adaptive immune system and its evolution are being presented in this book with the most current knowledge, ideas and speculations. The major elements of genetic conservation and specific variations of that theme have helped elucidate the accumulation of the genetic, molecular, and biological data across various classes of vertebrates and phyla within the animal kingdom. This book used a much more general and integrated envisioning of some of the scenarios that linked together the genome evolution and the origin of the receptors and the differentiation of the lymphocyte. This book is also a collection of chapters that are centered on in phylogeny of the immune system that was written by

scientist who are at the forefront of the research. For the first time, this book presents the fresh mix of subjects and new approaches in a form of reviews. In this area, the book delineates the current and controversial issues that state clearly that the book is comprehensive. There are several scenarios linking together genome evolution and the origin of receptors and differentiation of lymphocyte lineage are now envisioned at a much more general and integrated level than ever before. This book delineates the current and controversial issues in the phylogeny of the immune system and it present s a fresh mix of subjects and approaches presented for the first time in the form of reviews.