Ependymal

Extrahypothalamic OX-B-like immunoreactivity, reminiscent to that of CRF, has been described in clustered GABAergic neuronal populations, in the lateral division of central nucleus ofthe amygdala, the bednucleus of the stria terminalis, and in the hippocampus. Moreover, ectopic expression of preproorexin mRNA in the gut, ependymal cells, neuroblastomas, and of orexin receptors in adrenal gland, cancer and hematopietic stem cells suggests yet unexplored roles of orexins as paracrine factors controlling blood-brain barrier, and tumor or stem cell function. 

The histaminergic neurons have several well-developed primary and secondary dendrites that overlap with each other. Furthermore, long dendrites from histaminergic neurons located close to the mammillary recess or to the basal surface of the mammillary body appear to penetrate into the ependymal layer and make contact with cerebrospinal fluid. Thus, it is likely that neuroactive substances such as cytokines, present in the cerebrospinal fluid, may influence the discharge activity of TMN neurons (Wada et al., 1991). Unlike the dopaminergic neurons, which are known to release dopamine from their dendrites, there is no evidence that these histaminergic dendrites store and/or release HA. 

Ependymal cells line the brain ventricles and the spinal cord central canal 15... 

Ependymal cells abut layers of astrocytes, which in turn envelop neurons, neurites and vascular components. In addition to neurons and glial cells, such as astrocytes and oligodendrocytes, the normal CNS parenchyma contains blood vessels and microglial cells, the resident macrophages of the CNS. 

FIGURE 1-17 The surfaceofan ependymal cell contains basal bodies (arrows) connected to the microtubules of cilia, seen here in longitudinal section. Several microvilli are also present. X37,000. Inset Ependymal cilia in transverse section possess a central doublet of microtubules surrounded by nine pairs, one of each pair having a characteristic hooklike appendage (arrows). X 100,000. 

FIGURE 1-18 A typical desmosome (d) and gap junction (g) between two ependymal cells. Microvilli and coated pits (arrows) are seen along the cell surface. X35,000. 

AQP4 is the major water facilitator in brain and is most concentrated in astrocyte endfeet, but AQP4 has not been found in neurons. It is localized to basolateral surfaces of ependymal cells and along the entire plasma-lemma of astrocytes, including processes that ensheath... 

Ternaux, J. P., Hery, F., Hamon, M., Bourgoin, S., and Glowinski, J. (1977) 5-HT release from ependymal surface of the caudate nucleus in encephale isole cats. Brain Res., 132 575-579. 

IHC shows constitutive and inducible CYPIBI in artery smooth muscle cells, leptomeninges, cerebral arteries/arterioles, and ependymal cells (Granberg et al., 2003). 

Ependymal cells, which line the cavities of the central nervous system. 

Figure 14.4 Different types of glial cells. Astrocytes connect capillaries and neurones. Fibrous astrocytes, with less branching and more filamentous processes, occur mainly in white matter while protoplasmic astrocytes are located principally in the grey matter. Oligodendrocytes form the myelin sheath by wrapping themselves around axons. The connection between the myelin sheath and the oligodendrocyte is permanent and provides material for the myelin sheath. Microgliocytes (microglia) are the phagocytes of the nervous system. The ciliated ependymal cells line the cavities of the central nervous system.

Li, Y., Chen, J., Chopp, M. (2002). Cell proliferation and differentiation from ependymal, subependymal and choroid plexus cells in response to stroke in rats. J Neurol Sci, 193, 137-46. 

Chiasson, B.J., Tropepe, V., Morshead, C.M., van der Kooy, D. (1999). Adult mammalian forebrain ependymal and subependymal cells demonstrate proliferative potential, but only subependymal cells have neural stem cell characteristics. J Neurosci, 19, 4462-71. 

Wang, S., Roy, N.S., Benraiss, A., Goldman, S.A. (2000). Promoter-based isolation and fluorescence-activated sorting of mitotic neuronal progenitor cells from the adult mammalian ependymal/subependymal zone. Dev Neurosci, 22, 167-76. 

The Ki-67 antigen was originally identified by its cell-cycle-related expression and is now considered to be a more specific marker for cell proliferation and cell cycling than is PCNA (Gerdes et al., 1984). This is supported by the observation that ependymal cells,... 

In light of the above-mentioned limitations, it seems that Ki-67 is a more specific marker for cell proliferation than PCNA. This suggestion is strengthened by the observation that ependymal cells (which are unable to regenerate) are PCNA positive but Ki-67 negative (Funato et al., 1996). In view of the aforementioned and other factors known to influence PC 10 labeling of PCNA, it should not be accepted uncritically as a marker of cell proliferation in sections of paraffin-embedded tissues. 

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