Ectopic vas deferens.

Two infants with ectopia of the vas deferens are described. To date 11 cases have been reported, comprising a total of 13 ectopic vas insertions, 2 of which are bilateral. A classification of 2 types of ectopic vas is presented with a discussion of their relationship to ureteral ectopias. An embryological hypothesis of a proximal vas precursor segment of the wolffian duct is related closely to Stephens' theory of ureteral development.