This book introduces readers to the fascinating interaction of specialized gamete cells, forming the early embryo and a blueprint of new life. Readers will gain a thorough understanding of the complex physiological events and mechanical processes - such as ionic regulation, metabolism and intracellular signalling - to decipher cause and effect in fertilization. Wide-ranging in its approach, this book describes fertilization as a highly conserved mechanism throughout the animal kingdom, taking case studies from echinoderms, ascidians, amphibians and mammals through to other phyla. An excellent companion to undergraduate and postgraduate students of medicine, veterinary and biological sciences, this text provides an underpinning of the mechanisms of fertilization that inform assisted reproduction practice and research in medicine and agriculture. It explores the detailed phases before fertilization: the oocyte as a quiescent cell, attracting its partner gamete, followed by a cascade of pre-determined physiological events, to form the dynamic zygote cell; setting the scene for the early embryo, and beyond.