ICC stained sections from normal, MPS I, and MPS I BMT-treated cats. Top row panels (a, b, and c) were stained by ICC for GM2. Bottom row panels (d, e, and f) were stained for GM3. Images of the normal cat (a and d) show virtually no GM2 or GM3 staining. MPS I-affected sections (b and e) show significant intracellular storage of gangliosides, in neurons (arrows) and glia (arrows heads). Neurons and glia in BMT-treated animals remained immunoreactive but the degree of staining appears less intense, a difference particularly evident for GM3 ganglioside, with fewer deep cortical neurons appearing stained (panel f).