This review describes recent research into the cause of testicular descent and discusses two controversial theories on the mechanism. New animal models of cryptorchidism are described which shed light on the possible aetiology. A brief summary is given of current management, highlighting the controversies of timing of surgery, use of hormone therapy and congenital versus 'acquired' undescended testes. New information about germ cell development in the postnatal testis is changing the way we view treatment and the ultimate prognosis.

Inhaltsangabe1 Introduction.- 2 Normal Testicular Descent.- 2.1 Two-Stage Hypothesis.- 2.2 Role of Müllerian Inhibiting Substance/Anti-Müllerian Hormone.- 2.3 Genitofemoral Nerve Hypothesis.- 2.4 Role of Calcitonin Gene-Related Peptide.- 2.5 Hypothesis to Explain Normal Testicular Descent.- 3 Cryptorchidism.- 3.1 Animal Models.- 3.2 Hypotheses of Aetiology.- 3.3 Recognizable Causes of Cryptorchidism.- 3.4 Congenital vs Acquired Cryptorchidism.- 3.5 Effects of Cryptorchidism.- 4 Management of Cryptorchidism.- 4.1 Rationale for Treatment and Its Timing.- 4.2 Surgical Treatment.- 4.3 Hormonal Treatment.- 4.4 Possible New Approaches to Treatment.- 5 Conclusions.- 6 References.- 7 Subject Index.