A morphometric study of placenta in fetal congenital nephrotic syndrome of Finnish type.

A qualitative light microscopic study was performed on 9 fetal congenital nephrotic (CNF) and 13 control placentas obtained from legal pregnancy terminations or spontaneous abortions at 16-20 weeks of gestation. From this material 6 CNF cases and 6 age matched controls were selected for morphometric analysis. The total villous volume and the ramification pattern of the villi were similar in CNF and controls. A significant decrease in the villous vascularization was found in CNF. It is suggested that disturbed oxygen exchange due to poor development of the villous vessels causes a compensatory hyperplasia of the placenta at birth in CNF. Electron microscopic investigation was performed on three CNF and two control placentas. No changes typical of fetal CNF were found in the villous ultrastructure. The syncytial microvillous projections seemed to be more numerous and longer in CNF, otherwise the structure of the trophoblastic layer of the villi and the lining of the subtrophoblastic vessels were identical in CNF and controls.