Vitelline veins the developing liver and broken up by it into a plexus of small capillary-like vessels termed sinusoids. The vitelline veins give rise to Inferior mesenteric vein, Ciliac trunk The branches conveying the blood to the plexus are named the venae advehentes, and become the branches of the portal vein. The vessels draining the plexus into the sinus venosus are termed the venae revehentes, and form the future hepatic veins. Ultimately the left vena revehens no longer communicates directly with the sinus venosus, but opens into the right vena revehens. The persistent part of the upper venous ring, above the opening
Helicine arteries of penis in increased levels of cyclic guanosine monophosphate (cGMP). cGMP in turn triggers relaxation of the smooth muscle and results in dilation of blood vessels. This signal is terminated when cGMP is broken down by the enzyme cGMP specific phosphodiesterase type 5 (PDE5), the enzyme that is targeted by sildenafil and other drugs that treat erectile dysfunction. By preventing PDE5 from breaking down cGMP, the effects of NO are amplified and vasodilation occurs, thus resulting in increased penile erection. Helicine arteries of penis The helicine arteries of penis are arteries in the penis. They are found in the corpora cavernosa penis.