Other findings indicating mesothelial lineage of the malignant cells are filaments, which often surround the nucleus, and cytoplasmic, coarse tonofilaments
, the latter correlating to the expression of cytokeratin 5 and a finding of squamoid differentiation.
They had relatively few microorganelles and rare tonofilaments
, and their cell membrane formed tight junctions or desmosome-like junctions with adjacent cells (Figures 2(a) and 2(b)).
 identified what were thought to be tonofilaments
embedded in an amorphous matrix indicating that disruption of epidermal or follicular tonofilaments
may play a role in the pathogenesis.
The spindle cells contain desmosomes and tonofilaments
, supporting their squamous cell origin.
Second, matrices of numerous penetrative fibers, or tonofilaments
, composed of bundles of ca.
Electron microscopy shows the basaloid component to have desmosomes, rare tonofilaments
and loose stellate granules or replicated basal lamina within the cystic spaces.
Electron microscopic findings include lipid-like vacuoles in the corneocytes and granulocytes reduction in tonofilaments
and irregular keratohyalin granules.
Apoptotic bodies rich in tonofilaments
were not found.
The finding of epithelial elements, mature desmosomes, and tonofilaments
in the original neoplasm secured the diagnosis of spindle-cell squamous carcinoma.
The UTROSCTs have diverse findings under the electron microscope, including both epithelial (desmosome-like junctions, tonofilaments
, lumina formation, and microvilli) and sex-cordlike features (nuclear indentation, abundant intracellular filaments, sparse to moderate rough endoplasmic reticulum [granulosa cells], and abundant intracytoplasmic lipid [Sertoli]), along with aggregates of perinuclear filaments with concordant IHC positivity for markers of epithelial and sex cord differentiation.
Prominent microvilli, desmosomes and tonofilaments
if seen are highly suggestive of ATE (14).
Moreover, dividing cells are also connected to their neighbors with intercellular junctions and retain SLSs or short bundles of tonofilaments
in their cytoplasm (Fig.