Left-sided cryptorchidism in mice with Wilms' tumour 1 gene deletion in gubernaculum testis.

A significant number of patients with germline mutations in the Wilms' tumour 1 (WT1) gene, a transcriptional factor essential for early renal and gonadal development, display cryptorchidism or non-scrotal testis position. We show here that WT1 is expressed during development in the mouse gubernacular ligament connecting the testis to the abdominal wall. Conditional inactivation of Wt1 in the gubernaculum (GU-WT1KO animals) resulted in abnormal differentiation of the gubernacula during development and, in about 40% of adult males, unilateral, always left-sided, cryptorchidism.