In 1990 the SRY gene was isolated. This volume encompasses the knowledge and developmental processes involved in vertebrate sex determination since then. It studies five genes essential for early mammalian gondal development in detail: SF-1 and WT-1 and their roles in early events in gondal development; SRY and SOX9 in testis determination; and the anti-testis gene DAX-1. The book also covers the role of genes in sex determination in marsupial mammals, birds, reptiles, amphibians and fish. It reviews the different sex-determining mechanisms, genetic and environmental, that operate in different vertebrate classes.