Its roof plate appeared as a single layer of neuroepithelial
ependymal cells which covered by tela choroidea (vascular mesenchyme and the pia mater).
Most of the CSF is produced by the choroid plexus, while small amounts are secreted by the
ependymal surfaces of the ventricles and by the arachnoid membranes (3).
Anti-GFAP stains astrocytes,
ependymal cells and corresponding tumours and studies have shown usefulness of GFAP in distinguishing neoplasms of astrocytic origin and in differentiating gliomas from metastatic lesions in the brain.
Ependymal loss, subpial necrotic lesions, loss of myelin, axonal swellings, necrosis, and reactive leukodiapedesis were seen.
The histogenesis of this kind of tumor is still uncertain, but ultrastructural data indicate a possible derivation from
ependymal cells (6, 7, 10), which may represent a subtype of ependymoma (7, 10).
Ependymal cells of chordate larvae are stem-like cells that form the adult nervous system.
Enlargement of arachnoid cysts can be caused by fluid secretion from
ependymal cells, fluid ingress secondary to an osmotic gradient, trapping of fluid by a ball/valve mechanism, (3) and strenuous venous pulsation produced during Valsalva manoeuvres.
The 2007 World Health Organization (WHO) classification of primary brain tumors distinguished four types of
ependymal tumors based on their histological appearance: subependymoma (WHO grade I), myxopapillary ependymoma (WHO grade I), ependymoma with cellular, papillary and clear cell variants (WHO grade II) and anaplastic ependymoma (WHO grade III) [2].
In lesions with insufficient blood supply, reactive changes, local calcifications, and
ependymal type cystic degeneration may be seen.
These results were comparable to a previous study conducted by Ahmed Z et al.14 which showed that the frequency of GBM were 71.37%, oligodendrogliomas 15.06%, ependymomas 8.77% and mixed 3.16%.In another study, gliomas of astrocytic, oligodendroglial and
ependymal type accounted for more than 70% of all brain tumours with glioblastoma being most frequent (65%) and malignant histological type.15
Previous work using light microscopy analysis has demonstrated the harmful effects of the same dose of MeHg [30], where it caused reduction in the thickness of the
ependymal, mantle, and marginal layers.
[30] reported the presence of neural stem cells around the
ependymal membrane of the spinal cord.