Figure 2.

EM of patient with CINAC from Paraguay. (a) Proximal epithelial cell containing enlarged dysmorphic single-membrane bound lysosomes with nonmembrane-bound, electron-dense, rounded/irregular aggregates dispersed throughout a light to medium-uniform, electron-dense matrix. (b and c) Details of a. (d) PTC containing a large dysmorphic lysosome (asterisk). Note the numerous associated smaller round, oval, and mildly dysmorphic lysosomes in the cytoplasm (arrows). (e) Higher magnification of the largest dysmorphic lysosome (asterisk) showing dispersed electron-dense aggregates in a medium to pale electron-dense matrix. (f) Same image as e with dotted delineation of the large lysosome. These granules were previously identified as lysosomes by performing TEM-EDX on PASM-stained sections.⁴ This technique allowed to confirm that the black silver and gold deposits of the PASM staining indeed were present in the argyrophilic granules, with the latter being positive for lysosomal markers on immunofluorescence.⁴ The biopsy sample was fixed in glutaraldehyde, postfixed in OsO₄, and embedded in epoxy resin. Ultrathin sections were collected on carbon-coated formvar grids and stained with uranyl acetate and lead. EM, electron microscopy; OsO₄, osmium tetroxide; PASM, Periodic acid–Schiff methenamine; TEM-EDX, transmission EM energy-dispersive X-ray spectroscopy.