Ultrastructure of the villi and fetal capillaries in placentas from smoking and nonsmoking mothers.

The ultrastructure of placental villi from 10 heavy smokers (10 greater than or equal to cigarettes per day) was compared with that of 16 nonsmokers (never smoked). Thickening of the basement membrane and increase in collagen content of the villous stroma was found. The fetal capillaries were fewer in number and with decreased lumen either due to oedema or contraction of the endothelial cells. All cells, both in the fetal capillaries as well as syncytiotrophoblast and cytotrophoblast contained large amounts of filaments and fibrillae possibly capable of cell contraction. Thus a result of these findings might be a decreased placental flow in smokers.