An ultrastructural and ultrahistochemical study of the placenta of the diabetic woman.

An ultrastructural and ultrahistochemical study has been made of placentae from seven women, all of whom were established diabetics before the onset of pregnancy. None of these women had suffered from any of the hypertensive complications of pregnancy. Patchy focal syncytiotrophoblastic necrosis was evident and indirect evidence of syncytial damage was seen in the form of marked cytotrophoblastic hyperplasia. The syncytial necrosis appeared to be lysosomally mediated, possibly as a result of altered intracellular pH. Occasional cytotrophoblastic cells also showed degenerative changes. Most of the villous trophoblast was, however, morphologically normal and showed features suggestive of normal or increased synthetic, transfer and excretory activity. Focal thickening of the villous trophoblastic basement membrane was seen and this did not appear to be due to deposition of immune complexes. The endothelial cells of the villous capillaries appeared unduly immature but no evidence was seen of immune complex deposition in these vessels or of diabetic angiopathy. It is concluded that the diabetic's placenta shows a consistent pattern of abnormalities which appear to be a direct result of the diabetic state.