• Placentae;
  • chorionic villi;
  • fetal stem vessels

ABSTRACT: Cytoskeletal proteins (i.e., cytokeratins, vimentin, actin, and desmin) are normally present in the placental chorionic villi and are related to the maintenance of the villous shape, and to the ability of the villi to contract and permit a normal blood flow. In areas of villitis of unestablished etiology, the normal reactivity of these proteins in the villous core around fetal stem vessels disappears, and an increased number of cytokeratin positive cells is identified. The vascular damage in stem villi with villitis could develop ischemia in the villous tree promoting cytotrophoblast proliferation. Increased numbers of these areas could be related with the appearance of abnormal pregnancies.