It has to get through the vessel wall into the bloodstream.

It causes the smooth muscle in the vessel wall to relax.

Blood had begun to work its way between the layers of the vessel wall.

Holes appear in vessel walls and blood leaks out into the tissues.

It measures the pressure of the blood on vessel walls in between heart beats.

Now it is shown in conjunction with the vessel wall.

Into the flames it went again until the color melted into the vessel wall.

The vessel wall was still at a comfortable distance, but it had changed in appearance.

David made a small incision in the vessel wall between the tapes.

The cracks grew through the vessel wall as a result of hydrogen pressure cracking.