[Ultrastructure of the blood platelets in Wiskott-Aldrich syndrome].

The platelets of 3 undoubted cases of Wiskott-Aldrich syndrome and of 1 suspected case have been investigated from the ultrastructural point of view. The platelet defects were striking by their small size, variable and distorted shape with numerous microvillosities, degranulated cytoplasm (scarce granules or lysosomes, rare mitochondria) and the distension of the canalicular system. The specificity of the ultrastructural platelet defects was discussed in comparison with other hereditary platelet diseases. An attempt was made to find out the meaning of the platelet alterations in this immunologic deficiency.