The placenta in pre-eclampsia and intrauterine growth restriction: studies on exchange surface areas, diffusion distances and villous membrane diffusive conductances.

We test the null hypothesis that the morphometric diffusive conductance of the placental villous membrane does not alter in pregnancies complicated by intrauterine growth restriction (IUGR) or pre-eclampsia (PE). Placentas were collected from cases of normotensive IUGR, pure PE, PE+IUGR and from control pregnancies. Microscopical fields on formalin-fixed, trichrome-stained histological sections were randomly sampled for location and orientation. Using stereological methods, the exchange surface areas of peripheral (terminal and intermediate) villi and their fetal capillaries and the arithmetic and harmonic mean thicknesses of the villous membrane (maternal aspect of trophoblast to luminal aspect of vascular endothelium) were estimated. An index of the variability in thickness of this membrane, and an estimate of its oxygen diffusive conductance, was derived secondarily. Group comparisons were drawn using two-way analysis of variance to identify main effects (of PE or IUGR) and interaction effects (between PE and IUGR). PE did not have significant effects on placental morphology and there were no significant effects of PE or IUGR on membrane thickness or its variability. In contrast, IUGR (with or without PE) was associated with reduced surface areas and this was the principal factor leading to a smaller membrane diffusive conductance in these placentas. When account was taken of fetal mass, specific conductance showed no effects of PE or IUGR despite the mass-specific conductance in pure IUGR placentas appearing to be smaller than that in controls. The decline in total conductances is indicative of perturbations operating at the levels of villous trophoblast and fetal vasculature and these may contribute to fetal hypoxic stress.

Morphometric evidence that villous development and fetoplacental angiogenesis are compromised by intrauterine growth restriction but not by pre-eclampsia.

The aim of this study was to compare morphometric measures of villous development, villous capillarization, fetoplacental angiogenesis and capillary lumen remodelling in normal pregnancies with those complicated by intrauterine growth restriction (IUGR) with and without preeclampsia (PE). To this end, term placentas from control pregnancies (n = 9) and cases of IUGR alone (n = 5), PE alone (n = 5) and IUGR with PE (n = 5) provided random samples of tissue. These were fixed in formalin and Masson trichrome-stained wax sections were analysed stereologically. Overall growth of peripheral villi and fetal capillaries was assessed by estimating total volumes, surface areas and lengths. Villous capillarization was monitored using volume, surface and length densities and capillary:villus surface and length ratios. Measures of villous maturation and capillary lumen remodelling comprised mean cross-sectional areas, perimeters and shapes (perimeter(2)/area). Between-group comparisons were drawn using two-way analysis of variance. IUGR was associated with abnormal growth of villi and fetal capillaries. Reduced villous growth was not accompanied by changes in measures of villous capillarization or maturation and reduced capillary growth was not accompanied by changes in lumen calibre or shape. In contrast, PE was not associated with any main or interaction effects on placental morphometry. It is concluded that IUGR, but not PE, is associated with impoverished villous development and fetoplacental angiogenesis. The latter is due to production of fewer and/or shorter capillary segments (rather than a decrease in capillary calibre), does not affect villous capillarization and is not accompanied by luminal remodelling.

Familial amyloid polyneuropathy in a Sri Lankan family.

A woman who presented with features of peripheral sensory, motor and autonomic neuropathy and amyloid deposits in the vitreous due to familial amyloid polyneuropathy (FAP) is described. Her father had died of a similar illness and one of her brothers and her two children had lesions suggestive of early amyloid deposits in the vitreous. Reports of familial amyloidosis are rare from Asian countries and it has not been reported in Sri Lanka previously.