Fig. 1

Ultrastructural integrity of human tissue samples from different sources. Ultrastructural integrity is low in postmortem material from a control donor, though major organelles such as nuclei (N) remain identifiable (low-magnification view, a). At high magnification, synapses (arrowhead) are damaged but clearly defined (b). Material from an Angelman syndrome donor is virtually uninterpretable (reflecting the practical difficulty of obtaining and curating such material), though damaged mitochondria and traces of nuclear structure remain (N in panel c); hints of synaptic specializations may be identified even in this material (arrowhead, d). In contrast, tissue from biopsy specimens obtained during surgeries for epilepsy shows very good preservation, as documented by features including intact mitochondria, well-aligned rough endoplasmic reticulum, and intact chromatin (e). The well-preserved neuropil (f) contrasts with that of the autopsy specimens above. Tissue from case no. 5758 for a and b, 1494 for c and d, and Q1012 for e and f. Scale bar = 1 μm in a, c, and e and 500 nm in b, d, and f