Ultrastructural observations of chorionic villi at term in diabetic women.

An electron microscopic study has been performed on placentas from women with maternal diabetes. None of the patients had suffered from any of the hypertensive complications of pregnancy (White's class A). Most villous trophoblasts were morphologically normal and showed features suggestive of normal or increased synthetic transport and excretory activity. These cells appeared to be far more "active" than their counterparts in normal term placentas in that many contained Golgi bodies that were often associated with membrane-bound osmiophilic vesicles. Focal thickening of the trophoblastic basement membrane was seen. The endothelial capillaries contained an excessive number of microfibrillae and micropinocytotic vesicles and appeared unduly immature. Very abundant osmiophilic granules were seen in many villous components, such as syncytiotrophoblasts, stromal fetal endothelial cells, pericytes, Hofbauer cells and fibroblasts. These may have been concerned in the cross-transportation of materials between the maternal intervillous space and the fetal capillaries, rather than the incorporation of substances within them. These morphological changes did not show, however, any specific, constant or uniform pattern of abnormality attributable maternal diabetes.