Hemorrhagic endovasculitis-like lesion induced in placental organ culture

In organ culture, human chorionic villi develop vascular changes that resemble so-called hemorrhagic endovasculitis. The latter is a morphologic finding more prevalent in placentas of stillborn infants but seen also in those of liveborn infants, in whom the lesion is localized rather than generalized. We compared the histologic vascular changes in short-term organ cultures of 15 placentas (10 term, 5 preterm) with the naturally occurring vascular lesion in 6 placentas (2 liveborn, 4 stillborn). All organ cultures of placentas from liveborn infants developed hemorrhagic endovasculitis-like lesions in the fetal stem arteries; these lesions were present as early as 1 day and persisted for 7 days in culture. A mechanism common to both the in vivo and in vitro systems depending on hypoxia and vascular smooth muscle contraction may explain both the naturally occurring and tissue culture-induced lesions.