Book excerpt: This book provides a state of the art overview of all aspects of testicular descent and cryptorchidism, including the mechanisms of descent and the causes, consequences, diagnosis, and treatment of undescended testis. The advances in understanding that have been achieved over the past two decades are clearly explained, covering the latest genetic information on the causes of normal and abnormal testicular descent, the role of INSL3 in transabdominal migration, and the evidence that a neurotransmitter released from the genitofemoral nerve mediates androgenic control of inguinoscrotal descent. Exciting changes in the management of both congenital and acquired cryptorchidism, such as the widespread use of laparoscopy for impalpable testes inside the abdominal cavity, are fully described. Evidence for the benefits of orchidopexy within the first year of life is reviewed, and an individual chapter is also devoted to hormonal treatment. Throughout the book due attention is given to ongoing controversies and divergences of opinion. This new edition of Descent of the Testis will be a timely update and valuable reference for all who are involved in research into testicular descent and management of cryptorchidism.