Morphological characteristics of the terminal villi in placental failure.

A comparative morphological study of the placentas in spontaneous and induced pregnancy aggravated by placental failure was carried out. Placental failure manifested by shrinkage of the terminal villi, lesser number and section areas of their capillaries, and higher expression of vascular endothelium growth factor and endothelial NO synthase in the syncytiotrophoblast and villous endotheliocytes. The changes were more pronounced in pregnancy developing after in vitro fertilization.