Electron microscopy of umbilical cord endothelial cells in preeclampsia

We have studied by means of transmission electron microscopy the umbilical cord endothelial cells in 11 preeclamptic women. Endothelial cells exhibited oval, round, elongated, flattened, triangular or polygonal shapes. The nuclei displayed shallow and deep invaginations of nuclear envelope. The endoplasmic reticulum appeared highly dilated and vacuolated. The swollen mitochondria showed cristae fragmentation. Areas of focal necrosis were appreciated throughout the cytoplasm. A marked enlargement of subendothelial space and the presence of an electron dense granular material were also found. The findings reveal activation and injury of endothelial cells and disruption of endothelial cell layer.