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 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.
The finding of epithelial elements, mature desmosomes, and tonofilaments
in the original neoplasm secured the diagnosis of spindle-cell squamous carcinoma.
Prominent microvilli, desmosomes and tonofilaments
if seen are highly suggestive of ATE (14).
In the few studies where electron microscopy was used, some of the stromal cells had epithelial features, such as tonofilaments
and intercellular junctions, similar to squamous epithelial cells.
Moreover, dividing cells are also connected to their neighbors with intercellular junctions and retain SLSs or short bundles of tonofilaments
in their cytoplasm (Fig.
Ultrastructurally, (3-5) the main cells are characterized by cytoplasmic tonofilaments
and desmosome-like structures, while the neuroendocrine cells showed electron-dense secretory granules.
Cellular junctional complexes, including desmosomes and tonofilaments
, are scanty, and lumina (intercellular and intracellular) are usually absent.
In the cytoplasm, undulating filaments that were located close to the nucleus were most consistent with tonofilaments