Fig. 7

Ultrastructural morphology of neuronal storage material. Semi-thin section stained with toluidin blue of a neuron in the spinal cord anterior horn of patient 2 shows strongly stained storage material (a). Ultrastructural examination of the same neuron in a serial section (b-e) reveals a cluster of intracytoplasmic globular inclusions (delineated in b) consisting of amorphous osmiophilic material with high-density particles, lipid droplets (e; white arrowheads) and structures reminding of degraded membranous material (d and e; arrows). These inclusions correspond to lipofuscin granules in lysosomal residual bodies and remind of granular osmiophilic deposits (GRODs). Note the different polygonal shape of physiological Nissl substance (b; white arrowheads). Scale bar: 50 μm in a, 10 μm in b, 2 μm in c, 250 nm in d and e