Abstract
The present study was performed in dogs to determine the site preventing the backflow from the corpus cavernosum to the arterial vessels when the corporeal pressure rises more than the systemic pressure (rigid phase). We confirmed a great gradient (325 ± 81 mm Hg, mean ± SD) between the corporeal pressure and the deep arterial pressure; the latter was measured at the distal point over the tunica albuginea, namely within the corpus cavernosum. This finding indicated that the mechanism preventing the arterial backflow existed within the corpus cavernosum. This assumption was supported by our light-microscopic findings that the helicine arteries were closed in the rigid phase, whereas they were dilated when the corporeal pressure was lower than the systemic pressure (tumescence/full erection phase). The results suggest that the helicine arteries play an essential role in the prevention of the arterial backflow in the rigid phase.