vessel elements are dead cells that are part of
Vessel element At maturity the protoplast – the living material of the cell – dies and disappears, but the lignified cell walls persist. A vessel element is then a dead cell, but one that still has a function, and is still being protected by surrounding living cells.
Pericardium The fibrous pericardium is the most superficial layer of the pericardium. It is made up of dense and loose connective tissue,[2] which acts to protect the heart, anchoring it to the surrounding walls, and preventing it from overfilling with blood. It is continuous with the outer adventitial layer of the neighboring great blood vessels.