Abstract
Renal biopsy specimens from 11 women with severe pre-eclamptic toxaemia were examined by light and electron microscopy linked with immunofluorescence and immuno-electron microscopy. The part played by the mesangium in causing capillary loop thickening is stressed, and the progress of this 'strangulation' is illustrated. In contrast to the findings of most previous authors, IgM was demonstrated by direct immunofluorescence in all biopsy specimens, and its presence and site within the glomerulus were shown by immuno-electron microscopy in three cases.