Morphology of the placenta in fetal I-cell disease

Placentas were studied from three interrupted pregnancies of a mother whose first liveborn child had I-cell disease (mucolipidosis II). I-cell disease of the fetus was shown by investigation of the amniotic fluid, fetal cells and the aborted fetus in two pregnancies, but in the third case placenta was the only available product of conception. In every placenta extensive vacuolization of the syncytiotrophoblastic layer of the chorionic villi and chorionic mesenchymal cells was found. In electron microscopy the inclusions were identical to those of other tissues in I-cell disease. The importance of histological study of placenta in unexplained spontaneous abortions needs to be emphasized, since this may be the only way of detecing new cases of lysosomal storage diseases.