Search results for "Ependyma"
showing 10 items of 66 documents
Ultrastructural Pathology of Anaplastic and Grade II Ependymomas reveals Distinctive Ciliary Structures - Electron Microscopy Redux
2015
Ependymoma tumors likely derive from the ependymal cells lining the CNS ventricular system. In grade II ependymomas, tumor cells resemble typical ependymocytes, while anaplastic ependymomas are poorly differentiated. We studied three grade II and one anaplastic ependymoma, focusing on the ciliary structures. To unambiguously characterize the ultrastructure and number of cilia, we performed electron microscopy serial section analysis of individual cells. Differentiated ependymomas contained large basal bodies and up to three cilia, and lacked centrioles. Anaplastic ependymoma cells showed instead two perpendicularly oriented centrioles and lacked cilia or basal bodies. These findings could c…
White Matter Relationships Examined by Transillumination Technique Using a Lateral Transcortical Parietal Approach to the Atrium: Three-Dimensional I…
2019
Background Numerous lesions are found in the ventricular atrium (VA). Access is gained through many white matter tracts with great relevance and specific neurologic functions. It is important to understand the configuration of the most relevant structures surrounding this zone and, thus, select the safest entry zone on the lateral cerebral surface. Objective We studied the white matter layers traversed in the lateral transcortical parietal approach through the intraparietal sulcus (IPS), adding a transillumination technique. With this knowledge, we selected the safest highway to improve this particular approach. Methods An in-depth study of the white matter tracts was performed on 24 cerebr…
Cellular composition and organization of the spinal cord central canal during metamorphosis of the frogXenopus laevis
2017
Studying the cellular composition and morphological changes of cells lining the central canal during Xenopus laevis metamorphosis could contribute to understand postnatal development and spinal cord regeneration. Here we report the analysis of central canal cells at different stages during metamorphosis using immunofluorescence for protein markers expression, transmission and scanning electron microscopy and cell proliferation assays. The central canal was regionalized according to expression of glial markers, ultrastructure, and proliferation in dorsal, lateral, and ventral domains with differences between larvae and froglets. In regenerative larvae, all cell types were uniciliated, have a…
Serine/threonine-kinase 33 (Stk33) – Component of the neuroendocrine network?
2016
The present study was conducted to investigate the expression of serine/threonine-kinase 33 (Stk33) in neuronal structures of the central nervous system in rat and hamster as well as the presence of the protein in the brain of higher mammals, using a polyclonal antibody on cryosections of fixed brains. We found a distinct immunostaining pattern that included intense fluorescence of the ependymal lining of cerebral ventricles, and of hypothalamic tanycytes and their processes. We further observed intense staining of magnocellular neurons in the hypothalamic paraventricular, supraoptic and accessory neurosecretory nuclei, in particular the circular nuclei, and less intense stained neurons in …
Bi- and uniciliated ependymal cells define continuous floor-plate-derived tanycytic territories
2017
Multiciliated ependymal (E1) cells line the brain ventricles and are essential for brain homeostasis. We previously identified in the lateral ventricles a rare ependymal subpopulation (E2) with only two cilia and unique basal bodies. Here we show that E2 cells form a distinct biciliated epithelium extending along the ventral third into the fourth ventricle. In the third ventricle floor, apical profiles with only primary cilia define an additional uniciliated (E3) epithelium. E2 and E3 cells' ultrastructure, marker expression and basal processes indicate that they correspond to subtypes of tanycytes. Using sonic hedgehog lineage tracing, we show that the third and fourth ventricle E2 and E3 …
Neurovascular EGFL7 regulates adult neurogenesis in the subventricular zone and thereby affects olfactory perception
2016
Adult neural stem cells reside in a specialized niche in the subventricular zone (SVZ). Throughout life they give rise to adult-born neurons in the olfactory bulb (OB), thus contributing to neural plasticity and pattern discrimination. Here, we show that the neurovascular protein EGFL7 is secreted by endothelial cells and neural stem cells (NSCs) of the SVZ to shape the vascular stem-cell niche. Loss of EGFL7 causes an accumulation of activated NSCs, which display enhanced activity and re-entry into the cell cycle. EGFL7 pushes activated NSCs towards quiescence and neuronal progeny towards differentiation. This is achieved by promoting Dll4-induced Notch signalling at the blood vessel-stem …
The LIM Homeodomain Factor Lhx2 Is Required for Hypothalamic Tanycyte Specification and Differentiation
2014
Hypothalamic tanycytes, a radial glial-like ependymal cell population that expresses numerous genes selectively enriched in embryonic hypothalamic progenitors and adult neural stem cells, have recently been observed to serve as a source of adult-born neurons in the mammalian brain. The genetic mechanisms that regulate the specification and maintenance of tanycyte identity are unknown, but are critical for understanding how these cells can act as adult neural progenitor cells. We observe that LIM (Lin-11, Isl-1, Mec-3)-homeodomain geneLhx2is selectively expressed in hypothalamic progenitor cells and tanycytes. To test the function ofLhx2in tanycyte development, we used an intersectional gene…
The ependyma on the pineal of the guinea pig (Cavia cobaya)
1978
The proximal part of the epiphysis cerebri of the guinea pig is in close contact with the cerebrosopinal fluid of the third ventricle. A direct contact is not present as the pineal tissue is covered by a continuous ependymal layer. Two types of ependymal cells with different surface protrusions are discussed as being involved in possible interactions between the neuroendocrine tissue of the pineal organ and the cerebrospinal fluid. In addition, two different types of supraependymal structures are found on the ependymal surface of the habenulae and the wall of the third ventricle. Because of their morphological characteristics, these supraependymal structures are thought to be neural element…
Ultrastructure of the subventricular zone in Macaca fascicularis and evidence of a mouse-like migratory stream.
2009
Recent publications have shown that the lateral wall of the lateral ventricles in the Macaca fascicularis brain, in particular the subventricular zone (SVZ), contains neural stem cells throughout adulthood that migrate through a migratory pathway (RMS) to the olfactory bulb (OB). To date, a detailed and systematic cytoarchitectural and ultrastructural study of the monkey SVZ and RMS has not been done. We found that the organization of the SVZ was similar to that of humans, with the ependymal layer surrounding the lateral ventricles, a hypocellular GAP layer formed by astrocytic and ependymal expansions, and the astrocyte ribbon, composed of astrocytic bodies. We found no cells corresponding…
Postnatal Deletion of Numb/Numblike Reveals Repair and Remodeling Capacity in the Subventricular Neurogenic Niche
2006
Neural stem cells are retained in the postnatal subventricular zone (SVZ), a specialized neurogenic niche with unique cytoarchitecture and cell-cell contacts. Although the SVZ stem cells continuously regenerate, how they and the niche respond to local changes is unclear. Here we generated nestin-creERtm transgenic mice with inducible Cre recombinase in the SVZ, and removed Numb/Numblike, key regulators of embryonic neurogenesis from postnatal SVZ progenitors and ependymal cells. This resulted in severe damage to brain lateral ventricle integrity, and identified previously unknown roles for Numb/Numblike in regulating ependymal wall integrity and SVZ neuroblast survival. Surprisingly, the ve…