Increase of segments of elastic-type blood vessel walls in fetal placentalstem villi during pre-eclampsia at term

In recent studies we described the presence of elastic-type blood vessels w ithin trunci and rami chorii of human placental stem villi. For systemic an d pulmonary hypertension it is known that elastic fibres are enhanced in ar teries. The aim of our study was, therefore, to examine whether pre-eclamps ia may lead to an increase of elastic tissue fibres in blood vessel walls o f placental stem villi and whether there are differences in the thickness o f blood vessel walls within these villi when compared to normotensive pregn ant women. Twenty-six women with uncomplicated pregnancies and 25 patients with pre-eclampsia were investigated. Un-fixed cryostat serial sections wer e processed for conventional orcein staining and for the demonstration of a lpha-actin-immunoreactivity. The intensity of orcein staining of stem villu s blood vessel walls was evaluated by a semiquantitative score method. Sign ificant higher intensities of orcein staining (P<0.00001) were calculated f or blood vessel walls of placentae with pre-eclampsia. The amount of thick stem villus vessels (>41 mu m) increased during pre-eclampsia from 39 gesta tional weeks onwards. Our study demonstrates that segments of thick blood v essel walls and elastic-type vessel walls are increased in placental stem v illi of patients with preeclampsia. This reaction may protect the fetal pla cental vessels and avert an increase of the fetal hypertension.