Fertilization in Protozoa and Metazoan Animals

Reproduction is the origination of new organisms from pre-existing ones. Among more than 35 separated forms of reproduction including several types of gamogony, parthenogenesis, agamogenesis, fission and division, and plas­ motomy, the bisexual mode of reproduction via fertilization provides genetic variability that allows species to adapt quickly to competitive and constantly changing environments. Several excellent reviews and books have been written in the past to analyse the mechanisms of fertilization in different eukaryotic species. During the last few years, however, renewed attention has been paid to examining the process of oocyte fertilization at the cellular/molecular level not only within a single species/group but also through different phylogenetic lineages. As a result of this effort, knowledge of the molecular pathways used by oocytes and spermatozoa at fertilization has increased, but still many ques­ tions remain to be answered. Being aware of the necessity of providing an inte­ grated view of the process of fertilization, this book has been entirely devoted to reviewing the process of oocyte fertilization at the cellular/molecular level in two different and separated groups of eukaryotic organisms: protozoa and metazoan animals. The book is organized into six sections dealing with oocyte fertilization in protozoa, invertebrates, teleost fishes, amphibians, birds and mammals. These sections are followed by a summary/concluding chapter that provides a com­ parative overview of the process of fertilization in these groups of eukaryotes.

This book offers the reader an integrated point of view of fertilization in the animal kingdom. As the research at the molecular and cellular level is scarce compared to the huge diversity of animal species, for each phylum or class representative species have been chosen. Each phylum/class begins with a general description of the sexual and asexual reproduction strategies of the respective species, followed by a description of the reproductive cycle as well as of its reproductive system. The main focus is on the cellular and molecular aspects of fertilization of all the selected representative species, and the book is fully illustrated with photographs and drawings to facilitate understanding.