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Figure 1.
Fig. 1. Images of desmosomes from neonatal mouse epidermis. (A)
Low-magnification image showing an irregular border between
keratinocytes coupled by frequent desmosomes. This region of the
cell contains many ribosomes but, if the opaque discs are
construed as en face views of desmosomes, lacks organelles. (B
to D) Higher magnification images reveal the typical lamellar
structure of desmosomes. The membrane appears as a narrow white
zone; cadherin molecules appear as strands crossing the
extracellular space, which is bisected by an electron-dense
midline. Individual cadherins are difficult to identify because
of extensive superposition of these densely packed molecules
within the section; individual molecules are more readily seen
in ultrathin sections that are unsuitable for tomography but are
included in (13). A very dense plaque abuts the intracellular
face of the membrane and leads to a looser network of fibrous
densities that ultimately connect to bundles of intermediate
filaments. (E and F) Sections through the tomographic
reconstruction of desmosome "R" (see Table 1) cut parallel (E)
and perpendicular (F) to the untilted sample [e.g., (B)]. The
membrane is outlined in red, cadherin molecules in blue, two
zones of the cytoplasmic plaque in orange and light green, and
intermediate filaments in dark green. The perpendicular section
in (F) reveals the thickness of the plastic section and
illustrates that the resolution was quite isotropic [see also
(13)]. Scale bars, 500 nm (A), 100 nm [(B) to (D)], 30 nm [(E)
and (F)].
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