Figure 2.
Ultrastructure of htt bodies. MCF-7 cells were transiently transfected with FH969-100Q and immunostained for FLAG using the immunoperoxidase method. a, Electron micrograph of a cell with many htt bodies (arrows). Note the intense immunoperoxidase labeling at the rim but weak labeling in the core. The cytoplasm surrounding htt bodies is devoid of organelles. The nucleus (Nuc) is intact and has some small focal patches of immunoreactivity. The dense structure toward the top is the nucleolus. b, Higher magnification of boxed region at top right in a shows two htt bodies, a small one on the left and a larger one on the right. Note the intense immunoperoxidase reaction product (arrowheads) along the shell (S) of the large htt body. There is a mitochondrion (m) partly engulfed by the shell. Multivesicular bodies are in the core (C; arrows). The boxed region is shown in c. c, The core of the htt body contains tortuous fibrils (arrowheads) and multivesicular bodies (arrows). d, A cell contains one Flag-labeled htt body (arrow) that is in close proximity to several mitochondria. The nucleus (Nuc) has a few small patches of immunoreactivity. e, Higher magnification of a serial section through the htt body shown in d. Note the radiating fibrils in the core (C) and the less defined structure in the shell (S). Multilamellar-type autophagic bodies (a; arrows) abut the shell. f, Higher magnification of htt body in e. The dashed line is the approximate boundary between the shell (S), which is heavily labeled for Flag, and the core (C), which is not. There are radiating fibrils in the core (arrows). g, Higher magnification of the core-shell transition area shown in f. Shown are fibrils (arrows) and a globule (arrowhead). h, The shell of the htt body has immunoperoxidase-labeled globular structures that associate like beads on a string (arrowheads). Scale bars: a, d, 5 μm; b, e 1 μm; c, f, 0.5 μm; g, h, 100 nm.