• gubernaculum testis;
  • scrotum;
  • rat;
  • testicular descent;
  • vaginal process;
  • cryptorchism

In the rat the testicles are abdominal at birth: testicular descent and scrotal development are completed at about 40 days of age. To elucidate mechanisms of testicular descent the following operations were performed in newborn rats: Proximal and distal unlateral gubernaculotomy, and unilateral and bilateral orchidectomy. The operated rats were studied at various time intervals up to 100 days after the operations. Testicular descent was prevented if the distal part of the gubernaculum was cut, presumably because of interference with the growth of the vaginal processes. The gubernaculum does not pull the testicle down into the scrotum, since testicular descent occurred also after proximal gubernaculotomy. The gubernaculum is, however, necessary to anchor the descended testicle to the scrotal floor. Descent of epididymis took place also in the absence of a testicle on the same side. We propose that distal gubernaculotomy can be used in rats to produce an experimental model for studies of cryptorchism.