Ultrastructure of the human placenta at term. Observations on placentas from newborn children of smoking and non-smoking mothers.

The placenta was chosen as a possible model for evaluating the vascular injury and tissue injury provoked by tobacco smoking in the human body. Full term placentas from 4 smokers and 3 non-smokers were studied in the transmission electron microscope. Pronounced changes were found in the group of smokers. The characteristic findings were broadening of the basement membrane of the placental villus, increase in collagen content of the villus, decrease in vascularisation and intimal changes in the villous capillaries and arterioles, with pronounced intimal oedema. Since similar changes have been reported previously from human umbilical arteries, and since these changes also can be induced in animal arteries by exposure to carbon monoxide or perfusion with nicotine, this study supports the concept that tobacco smoking is harmful to the human vascular system and tissues.