Human arachnoid villi and
meningiomas are known to have gap junctions formed by
connexin (Cx)
proteins. We examined the expression and localization of Cxs in normal human arachnoid villi and
meningeal tumors (
meningiomas and
hemangiopericytomas) by immunohistochemistry and Western blots. In arachnoid villi, strong immunopositivity for connexin26 (Cx26) and
connexin43 (
Cx43) was detected in the cap cell layer, cap cell cluster, and central core. They were weakly expressed in the fibrous
capsule. In
meningiomas they were strongly expressed in the meningotheliomatous area and weakly positive in the fibrous area. None of them were expressed in
hemangiopericytomas. By immunoelectron microscopy, Cx26 and
Cx43 were distributed on the cell membranes in arachnoid villi and
meningiomas. In the Western blots in arachnoid villi and
meningiomas, Cx26 and
Cx43 were shown at bands with molecular weights of 26 kD and 42-47 kD, respectively. The degree of positivity for Cxs was different between subtypes of
meningiomas. These findings suggest that expression of Cx26 and
Cx43 might be related to the differentiation of the arachnoid villi and
meningiomas, and exhibit the different origin of various subtypes of
meningiomas. We proposed that Cx expression is one of the useful markers for the differentiation of
meningioma and
hemangiopericytoma.