This new edition provides an update on the molecular mechanisms that regulate spermatogenesis. In addition to the rodent as a study model, chapters also include research on studies in humans. It includes the latest approaches of studying spermatogenesis, such as the use of bioinformatics, molecular modeling and others which are not commonly found in published materials. It also reviews the latest developments in the field, such as studies on the role of regulatory RNAs on spermatogenesis. Due to the declining fertility rate among men, a brand new chapter highlights the impact of environmental toxicants on spermatogenesis.