Ultrastructural changes in the placenta of the ewe after long-term intravascular infusion of 2-bromo-alpha-ergocryptine (CB154) into mother or fetus.

The fine structural appearance of the placenta of the ewe has been examined following long-term infusion of CB154 into either the fetus or the pregnant ewe. Binucleate cells which usually contain aggregations of spherical membrane-bound electron-dense inclusions, are a characteristic component of the chorionic epithelium of the sheep. Following CB154 infusion into either the fetus or ewe at 111 to 137 days of gestation, binucleate cells were partially or completely depleted of the droplets which are present in binucleate cells of control animals at a similar gestational age. No obvious changes in the maternal epithelial syncytium were observed after CB154 administration. Infusion of CB154 into the fetus alone was also followed by degenerative changes in some binucleate cells which ranged from condensation of nuclei to complete cell fragmentation. Either a direct or an indirect action of CB154 on binucleate cells is suggested by these observations. Hypoprolactinaemia followed CB154 infusion in all treated animals; its possible influence on binucleate cell activity is discussed.