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

In recent studies we described the presence of elastic-type blood vessels within trunci and rami chorii of human placental stem villi. For systemic and pulmonary hypertension it is known that elastic fibres are enhanced in arteries. The aim of our study was, therefore, to examine whether pre-eclampsia may lead to an increase of elastic tissue fibres in blood vessel walls of placental stem villi and whether there are differences in the thickness of blood vessel walls within these villi when compared to normotensive pregnant women. Twenty-six women with uncomplicated pregnancies and 25 patients with pre-eclampsia were investigated. Unfixed cryostat serial sections were processed for conventional orcein staining and for the demonstration of (alfa)actin-immunoreactivity. The intensity of orcein staining of stem villus blood vessel walls was evaluated by a semiquantitative score method. Significant higher intensities of orcein staining (P<0.00001) were calculated for blood vessel walls of placentae with pre-eclampsia. The amount of thick stem villus vessels (>41 (mo)m) increased during pre-eclampsia from 39 gestational weeks onwards. Our study demonstrates that segments of thick blood vessel walls and elastic-type vessel walls are increased in placental stem villi of patients with preeclampsia. This reaction may protect the fetal placental vessels and avert an increase of the fetal hypertension.