Mucolipidosis III (pseudo‐Hurler polydystrophy): Cytological and ultrastructural observations of cultured fibroblast cells

Cultured fibroblast cells from four patients with mucolipidosis III (pseudo‐Hurler polydystrophy) were examined by phase contrast, dark‐field and electron microscopy. Both phase and dark‐field microscopy revealed striking abnormalities in three of these patients which were indistinguishable from those seen in mucolipidosis II (I‐cell disease). While electron microscopy indicated that the structural alterations found in both mucolipidosis II and III may he due to an increased storage of material within the cytoplasm, clear differences in the ultrastructural morphology were detectable between the two disorders.