Radiolabeled testosterone (3H-T) was infused into the testes or left and right mesofuniculus (106 dpm) or injected into a testes (2 x 10(6) dpm). The 3H-T concentration was estimated 15 or 10 min after 3H-T infusion or injection, respectively, in the tissue samples collected from the prostate, seminal vesicles, caput and cauda epididymides, vasa deferentia and the mesofuniculi. The abdominal aorta and posterior vena cava were cannulated, and the posterior part of the body perfused with blood (at blood pressure 70-140 or 260-300 mm Hg in abdominal aorta) was used to study 3H-T transfer from the testes to venous blood and other male genital organs. The concentration of 3H-T found in the accessory genital glands, epididymes and vasa deferentia was affected by blood pressure in the abdominal aorta. The reduced blood pressure and partial blocking of blood supply to the genital organs (after ligation of both testicular arteries or the terminal part of the abdominal aorta) increased the concentration of 3H-T in accessory genital glands, vasa deferentia and epididymes. The removal of the mesofuniculi and vasa deferentia with their mesoducti reduced 3H-T concentration in the prostate, seminal vesicles and cauda epididymides. Both arterial trunks, testicular arteries and common iliac arteries, were shown to be connected by anastomoses in target organs so effectively, that supplying the male genital organs with blood by only one of them assures the transfer of testosterone from the testes to the epididymes, vasa deferentia, mesofuniculi as well as prostate and seminal vesicles. It was concluded that lymphatic vessels of the mesofunicules and of the spermatic cords as well as venous and arterial vasculature of the mesofunicules create a recently unknown pathway for the increase of testosterone supply from the testes to the epididymes, vasa deferentia and accessory genital glands of rats.