The phenomenon of unstable expression of gap junction's
proteins connexins remains a "visiting card" of astrocytic
tumors with various degrees of
malignancy. At the same time, it stays unclear what is detected by the positive expression of
connexins in astrocytic
tumors: gap junctions, hemi-channels, or
connexin proteins in cytosol. In the present work, for the first time, we demonstrate an ultrastructural evidence of gap junctions in
pleomorphic xanthoastrocytoma, a rare
primary brain tumor, the intercellular characteristics of which are poorly studied and remain very discursive and controversial. The primary
tumor mass was resected during
craniotomy from a 57-old patient diagnosed with
pleomorphic xanthoastrocytoma Grade II based on the histopathological analysis. The immunohistochemical study was conducted with primary
antibodies: Neurofilament,
Myelin basic protein,
Glial fibrillary acidic protein, and
Synaptophysin. For electron microscopic examination fragments of
tumor tissue were fixed in a
glutaraldehyde, postfixed in a 1% OsO4, dehydrated and embedded into resin. After the detailed clinical, histological, and immunohistochemical study we revealed some ultrastructural characteristics of the
tumor, as well as the first evidence of direct intercellular connection between the
tumor cells via gap junctions. Regularly arranged gap junctions connected the somas of xanthastrocytes with dark cytoplasm containing
lipid drops. Besides the localization between the cell bodies, from one to several gap junctions were found between the branches of xanthoastrocytoma in
tumor intercellular space in close proximity to
tumor cell. Our results may indicate gap junctions as a possible structure for intercellular communication between
pleomorphic xanthoastrocytoma cells.