Histological changes in the placenta induced by maternal alcohol consumption in the rat

To investigate the placental enlargement which accompanies maternal alcohol consumption during pregnancy, Sprague-Dawley rats were given 20% ethanol for 4 weeks prior to mating and 30% ethanol throughout gestation. Pair-fed controls received an isocaloric amount of corn starch and chow, with water ad libitum, and ad libitum controls received rat chow and water. On days 17, 18, 19 and 20 of gestation, placentas were removed for histological observation. On days 18-20, the placentas of alcohol-fed rats weighted significantly more than did those of controls, although there was no difference in weight on day 17. Giant cells in the basal zone were significantly increased in number and size in alcohol-fed rats compared to controls. Trophoblastic cells in the basal zone were significantly larger in the alcohol group than in the control groups except on day 17. The maternal blood channels in the labyrinth were wider and more filled with blood corpuscles in the alcohol group than in either control group. It is concluded that the increased weight of the placenta may be largely due to stagnated maternal blood cells in the labyrinthine blood channels and also to the increased number and size of giant cells and the enlarged trophoblastic cells in the basal zone.