Endothelial alterations in the constricting rabbit ductus arteriosus: relationship to smooth muscle cell bleb...

Light, scanning, and transmission electron microscopy of the constricting rabbit ductus arteriosus just before and after birth reveal that as the vessel contracts, its endothelial cells lift up and protrude into the lumen. This endothelial protrusion is associated with the reorientation of subendothelial smooth muscle cells and the appearance of smooth muscle cell cytoplasmic blebs or "ghost bodies," especially just beneath the endothelial cells and in the expanded subendothelial space. These blebs are relatively clear extensions of smooth muscle cell cytoplasm which occur when smooth muscle cells contract and they may play a role in the lifting, separation or removal of endothelial cells in the closing ductus arteriosus and other vigorously contracting vessels.