[Studies of structural changes in toxemic placentae].

To determine the pathogenesis and the pathophysiology of toxemia of pregnancy, we investigated ultrastructural changes in placentae. 1. Lumina of villous capillaries dilate in mild toxemia and narrow in severe toxemia as in premature delivery. Trophoblasts increase with the progress of toxemia. 2. Changes in capillaries and trophoblasts appear as a compensatory reaction at some parts of placenta and at others as dysfunction. 3. Villi of the toxemic placenta have few ramifications, and are similar to those of early gestation, but there are very few stromata. This is thought to be a maldevelopment of villi. 4. Ultrastructural changes are as follows; a) Luminal dilatation and/or narrowing of villous capillaries. b) Endothelial thickening of villous capillaries. c) Decrease in the number of slit-like capillaries. d) Increase in intermediate filaments. e) Endothelial projections like villi and vesicle in the lumen of the capillary. f) Enlargement of microvilli. g) Increase in the number of syncytial knots and cytotrophoblasts. h) Increase in the number of wrinkles on the villous surface.