Placental electron microscopy and histochemistry in a case of sialic acid storage disorder.

Morphological alterations in a placenta from a case of infantile sialic acid storage disease are described. Syncytiotrophoblast, villous capillary endothelial cells, amniotic and Hofbaüer cells were filled with membrane-bound inclusions which were either electron-lucent or contained fibrillogranular material. Hydrolysis of slides with neuraminidase demonstrated at six hours Alcian blue material which was not present in normal syncytium. The possibility that a storage disorder such as sialic acid storage disease can be accurately diagnosed by electron microscopy on chorion villous sampling at nine to ten weeks is emphasized.