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PubMed2003

Brain ischemia augments exo-focal transgene expression of adenovirus-mediated gene transfer to ependyma in hypertensive rats.

The ependyma is one of the feasible targets for gene transfer to the brain. Using two different replication-deficient recombinant adenoviral vectors, AdCMVbetaGal or AdRSVIL10, we examined effects of cortical brain ischemia on transgene expression in the ependyma after administration of the vector into the lateral ventricle of spontaneously hypertensive rats (SHR). Expression of the reporter gene lacZ at the lateral ventricle was detected by histochemistry for semiquantitative scoring or by biochemical assay for quantitative analysis. Ependymal cells in the ventricles expressed the transgene as early as 6 h after gene transfer in both sham treatment and ischemia treatment. In the sham treatment, the expression peaked at 12 h and slowly decreased toward day 4 and day 7. However, transgene expressions in the ischemic brain on day 4 and day 7 were significantly higher than sham treatment. In the biochemical assay, beta-galactosidase activity detected on day 4 at the periventricular area of the ischemic group (37 +/- 9 mU/mg protein) was significantly greater than that of the sham group (12 +/- 4, P < 0.01). In the enzyme-linked immunosorbent assay for gene transfer of interleukin-10 (IL-10), IL-10 in the cerebrospinal fluid (CSF) of the ischemic group (11,633 +/- 4322 pg/ml) was significantly greater than that in the sham group (2460 +/- 1486, P < 0.05) on day 5. These results suggest that transgene expression in the exo-focal remote area of ependyma is augmented by cortical ischemia, and the ependyma may be a promising target of gene transfer of brain ischemia.

Adenoviridae↗

PubMed1998

Curly fiber and tangle-like inclusions in the ependyma and choroid plexus--a pathogenetic relationship with the cortical Alzheimer-type changes?

The question of whether thread- and tangle-like inclusions of the choroid plexus (known as Biondi inclusions) are related to the cortical lesions in Alzheimer disease (AD) has been debated for almost a century, yet remains unanswered. Recently beta-amyloid protein was biochemically isolated from the plexus, indicating a possible pathogenetic relationship between the degenerative changes of the cerebral cortex and those of the plexus. The goal of the present study was to analyze whether or not a significant correlation exists between the occurrence of the cortical AD-type changes and those in the ependyma and choroid plexus. In 292 consecutive autopsy cases several cortical areas, the ependyma, and the choroid plexus were analyzed to look for AD-type changes and Biondi inclusions using histochemical staining techniques and immunohistochemistry. A semiquantitative analysis of the density of cortical AD-type changes showed that of the 292 cases, 63 had severe cortical changes, 23 moderate changes, and 142 discrete changes. In 64 cases no plaques or neurofibrillary tangles were found. The number of cases with thread- and tangle-like elements in the plexus and ependyma was more than 96% in the 3 groups with cortical AD-type lesions, but low in the group without AD-type cortical changes (19%). The pathological argyrophilic filaments accumulating in the ependymal layer and plexus had histochemical properties of amyloid and were immunoreactive with antibodies to P component, ubiquitin, fibronectin and Tau protein. They did not react with antibodies to neurofilament proteins. Ultrastructurally, they consisted of densely packed straight and paired helical filaments and closely resembled neurofibrillary tangles and neuropil threads. The highly significant correlation (chi2, p = 0.001; R = 0.85) between the occurrence of AD-type changes in the cortex and those in ependyma and plexus suggests a pathogenetic relationship.

Alzheimer Disease↗

PubMed1988

Ultrastructure of the mouse spinal cord ependyma.

This study was done in order to investigate the normal ultrastructure of well-preserved mouse spinal canal ependyma using light, scanning and transmission electron microscopy. The ependymal lining was found to consist of a simple, cuboidal epithelium essentially similar to the unspecialized cuboidal ependyma of the brain ventricles. Apart from great variation in kinociliary density, no intracellular difference was noted between the ependymal cells. In contrast to earlier findings, indications of the existence of zonulae occludentes between the apical part of the ependymal cells were observed. Our findings do not support the hypothesis of secretion or intracellular transport by the ependyma, or that the ependyma constitutes a significant diffusion barrier.

Animals↗

PubMed1985

The ependyma of the cat central canal, with particular reference to its mitochondria-containing bulbs.

The ultrastructure of the ependyma in the central canal of adult cats was examined in both the scanning and the transmission electron microscopes (SEM and TEM). The same morphological details were seen in the ependyma of the central canal as have so frequently been described in the ependyma of the brain ventricular system, for example bundles of cilia, single cilia, microvilli and occasional small cytoplasmic protrusions. The supraependymal cells and supraependymal nerve fibers found in the central canal also resembled those seen in the ventricular system. The most striking feature of the canal ependyma were the large, spherical bodies containing numerous mitochondria. They are therefore called mitochondria-containing bulbs. In sections the bulbs were seen to be connected by long, slender stalks to neurons in subependymal position. In some respects the mitochondria-containing bulbs resemble the processes of cerebrospinal fluid-contacting neurons.

Animals↗

PubMed1980

Tight junctions in the ependyma of the spinal cord of the urodele Pleurodeles waltlii.

The ependymal junction pattern in the spinal cord of postmetamorphic ribbed newts has been studied, using transmission electron microscopy of ultrathin sections of normal animals and of animals perfused through the IVth ventricle with lanthanum. Contrary to what has been observed in mammalian CNS, the ependyma of the urodelan spinal cord is furnished with tight junctions that seal the luminal border of the terminal bars. These occludens junctions are made up of two to seven punctate fusions of the plasma membranes. Lanthanum tracer remains restricted inside the lumen of the central canal, being stopped at the first punctate fusion on its way through the intercellular clefts. Beyond this point, the extracellular space contains no tracer material. Besides tight junctions, intermediate, desmosomal and gap junctions are also present. Gap junctions and desmosomes are not present in CSF-contacting neurons. It is suggested that ependyma with occluding junctions (special ependyma) overlay the regions of the CNS where the ependymal cells significantly modify the composition of both intercellular and cerebrospinal fluids, through secretory, transporting and permeability control activities.

Animals↗

PubMed1981

Cytochemical study on enzyme activity associated with cerebrospinal fluid secretion in the choroid plexus and ventricular ependyma.

Normal adult albino and Sprague-Dawley rats, under intraperitoneal Nembutal anesthesia, were used to demonstrate enzymatic activity in the choroid plexus and ventricular ependyma. The brain tissues were perfused or immersed with cold 2% glutaraldehyde and 8% sucrose in 0.1 M cacodylate buffer (pH 7.2-7.4) for 30 min and washed overnight in the same buffer solution., The choroid plexus (lateral and fourth ventricles) and ventricular ependyma (lateral ventricle) were trimmed from the fixed and washed brain tissues, which were frozen and sectioned. For histo- and cyto-chemical study, the sections were immersed in the following incubation media; for Na+, K+-ATPase (ouabain-sensitive, K+-dependent, p-nitrophenylphosphatase: p-NPPase) according to the one-step method of Mayahara et al. (1978): for Mg2+- ATPase, Wachstein-Meisel's incubation medium (1957); for adenylate cyclase (AC), following Araki and Saito's lead citrate method (1979). The cytochemical findings gave the following results. In the choroid plexus, the ouabain-sensitive electron-dense reaction products of NA+, K+-ATPase (p-NPPase) were strongly positive in the microvilli and along the inner surface of microvilli, without showing any Mg2+-ATPase and AC activities, and all three enzymatic activities were positive along the basal plasmalemmas and negative along the lateral and apical (not including microvilli) plasmalemmas. In the ventricular ependyma, Na+,K+-ATPase (P-NPPase) activity was not found, and the reaction product of AC was observed on the apical plasmalemmas and those of Mg2+-ATPase along the basal plasmalemmas. These cytochemical findings are helpful in understanding the regulation of cerebrospinal fluid production through Na+, K+-ATPase (p-NPPase) and cyclic AMP (AC).

4-Nitrophenylphosphatase↗

PubMed1985

Morphometric changes in alcoholic mice of neurons of areas 6 and 17 and ependyma of the subcommissural organ.

We have performed a karyometric study of the postnatal development of the subcommissural organ (SOC), the subjacent thalamic ependyma, and the pyramidal neurons of layer V of the motor and visual cortical areas, in alcoholic male albino mice, aged 25-100 days. Ethyl alcohol was added to the drinking water at a concentration of 20%, from birth until the day of sacrifice. Our results show that alcoholism affects the SOC ependyma and the motor cortex, and, apparently, does not affect the ventricular thalamic ependyma and the visual cortex. We suggest a neuroendocrine mechanism to explain the SOC answer, and a functional deprivation to explain the changes in the motor cortex.

Aging↗

PubMed1992

Regional differentiation of the human fetal ependyma: immunocytochemical markers.

The development of the ependyma from 6 weeks (wk) gestation to term was studied in 26 human fetuses and infants for immunocytochemical differentiation using antibodies against vimentin, several cytokeratins, glial fibrillary acidic protein (GFAP) and S-100 protein. Acridine orange-RNA fluorescence was uniform in all differentiated ependymal cells. Marked differences were demonstrated among various anticytokeratin antibodies. Vimentin was demonstrated in undifferentiated cells, particularly during mitosis, and persisted as the ependyma matured. It was strong in floor plate cells and processes forming the ventral median septum. Vimentin and cytokeratin CK-904 coexisted with other immunoreactive proteins but disappeared in a caudorostral gradient with maturation. At 8 wk gestation, GFAP was detected in roof plate cells and their processes forming the dorsal median septum. S-100 protein appeared as early as 6 wk and had a more restricted regional distribution than GFAP at all ages. It was strong in the basal plate ependyma of the spinal cord in young fetuses. The temporal and spatial distributions of the immunoreactive proteins studied correlate with evidence that fetal ependymal cells synthesize compounds that attract or repel axonal growth cones to prevent axons from entering the ventricles or deviating from programmed projection pathways. An additional role may be to induce the transformation of radial glial cells in the subventricular zone.

Biomarkers↗

PubMed1979

A quantitative study of cell proliferation in ependyma and choroid plexus in the postnatal rat brain.

Profliferative activity in forebrain ependyma aand choroid plexus epithelium was studied in rats aged up to 42 days by means of autoradiography after injection of [3H]-thymidine. Labelling indices were higher in the lateral than in the third ventricle, while values for choroid plexus epithelium were lower than those for ependyma. In all areas examined, labelling indices showed a similar pattern of decline in the first two postnatal weeks reaching by day 12 a level about 20-30% of that on day 1. This low level, corresponding to a turnover time of 130 days for ependyma, was maintained tereafter up to day 42, indicating the persistence of proliferation in the young adult.

Age Factors↗

PubMed1978

Ependyma and supraependymal structures in some areas of the fourth ventricle in the rat.

The ependyma was investigated in five areas of the rat ventricle system by means of both light and electron microscopy. The columnar, cuboidal and flattened types of the ependymal cells were mainly seen. All of them were seen in the fourth ventricle, while in the aqueductus cerebri and in the central canal the flattened type of the cell was lacking. An unusual variation as to the form of the ependymal cells was found on the roof of the fourth ventricle. Three groups of intraventricular structures were found in all investigated parts of the ventricle system: supraependymal globular structures containing irregularly arranged cristae, supraependymal protrusions appearing as homogeneous contents, and nerve profiles including nerve endings and nerve axons. The morphological characteristics of the ependyma and intraventricular profiles in the fourth ventricle allow to suppose a certain role of these structures in the exchange of various materials between the CSF, ependyma and neuropile.

Animals↗

PubMed1992

Estrogen receptor-immunoreactive glia, endothelia, and ependyma in guinea pig preoptic area and median eminence: electron microscopy.

The presence of estrogen receptors (ERs) in nonneural cells in brain, including glia, ependyma, and endothelia, has not previously been documented with electron microscopy. This study employed immunocytochemistry to investigate whether ER immunoreactivity (ER-ir) is present in glial, ependymal, or endothelial cells in the medial preoptic area (POA) and median eminence (ME) in the brain of gonadally intact female guinea pigs. Tissue sections through these regions were immunostained with monoclonal antibody H222 for ER localization using 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogen. ER-ir cells were identified ultrastructurally by the presence of distinct spicule-like TMB crystals in nuclei. While neurons constituted the clear majority of ER-immunopositive cells, labeled astrocytes, ependyma, and endothelia were also present. Distinct intranuclear TMB crystals were present in astrocytes at the anterior pole of the POA within the preventricular periventricular nucleus, anterior compact subnucleus of the medial preoptic nucleus (MPNa), and organum vasculosum of the lamina terminalis, indicating ER-ir. In the MPNa, cell counts performed at the ultrastructural level revealed that 9.6% (15 of 156) of the astrocytes were ER-ir. To further explore the relationship of ERs with astrocytes, ER/glial fibrillary acidic protein (GFAP) double labeling experiments were performed using TMB and diaminobenzidine tetrahydrochloride for ER and GFAP localization, respectively. These studies verified the presence of ERs in astrocytes at the anterior pole of the POA and demonstrated the presence of ERs in GFAP-ir cells in the ME. Cell counts at the ME showed that 23 of 50 (46%) GFAP-ir cells were ER-ir. ER-ir was also present in scattered ependymal cells lining the third ventricle at the POA and overlying the ME. Typically, approximately four to eight ER-ir ependymal cells were present around the perimeter of the third ventricle, although occasionally small aggregations of greater numbers of labeled cells were observed. Both common ependyma and cells morphologically identified as tanycytes were ER-ir. Some endothelial cells and vascular smooth muscle cells also contained ERs. While approximately 11% of the vessels were lined by ER-ir cells in sections through the MPNa and preventricular periventricular nucleus, approximately 15% of the vessels were labeled in the organum vasculosum of the lamina terminalis. In the ME a greater percentage (59%) of the vessels contained ER-ir endothelial cells. Collectively, these results indicate that in addition to regulating the activity of neurons, estrogen may affect brain function through effects exerted on astrocytes, ependymal cells, and endothelial cells.

Animals↗

PubMed1976

Surface ultrastructure of human ependyma.

Specimens of human ependyma obtained immediately after death were immersion-fixed and studied with a scanning electron microscope. Human ependyma is nearly identical in its surface ultrastructural features to the ependyma of other mammals.

Cerebral Ventricles↗

PubMed1988

Correlated electrophysiology and morphology of the ependyma in rat hypothalamus.

The ependyma lines the ventricular system of the vertebrate brain and spinal cord. Although its embryology and morphology have been studied extensively, little is known of its physiological properties, particularly in mammals. Tanycytes are modified ependymal cells that are found predominantly lining the floor of the third ventricle, overlying the median eminence. Their processes accompany and enwrap neuroendocrine axons that course from hypothalamic nuclei to terminals in the median eminence, but the significance of this interaction is not yet understood. Intracellular recording and injection techniques were used to study ependymal cells and tanycytes of the rat in the hypothalamic slice preparation after differentiating their respective regions morphologically. With extracellular [K+] = 6.24 mM, the mean membrane potential (+/- SD) for common ependyma was -79.9 +/- 1.40 mV and for tanycytes, -79.5 +/- 1.77 mV. Input resistances (Rin) were very low (much less than 1 M omega). Single-cell injection of Lucifer yellow revealed dye coupling among 2-70 ependymal cells and 5-48 tanycytes. In both freeze-fractured replicas and thin sections, large numbers of gap junctions were found between adjacent ependymal cells and between adjacent tanycytes. The observations of numerous gap junctions, extensive dye coupling and low input resistance demonstrated that both populations are strongly coupled networks. Perhaps for this reason, attempts to uncouple these cells using sodium propionate or CO2 were unsuccessful. Electrical stimulation of the arcuate nucleus did not elicit any detectable synaptic response in impaled tanycytes, so that the functional significance of synaptoid contacts between neuroendocrine neurons and the postsynaptic tanycytes is not yet apparent. Ependymal cells and tanycytes demonstrated a near-Nernstian response to changes in extracellular [K+] between 3 and 20 mM. This finding, as well as their high negative resting potential, low Rin, extensive coupling and absence of spontaneous electrical excitability demonstrate that ependymal cells possess numerous glial characteristics and may therefore have similar functions. In the hypothalamus, ependyma probably take up K+ released from adjacent endocrine neurons and shunt it to the ventricular space.

Animals↗

PubMed1985

Changes in the surface fine structure of ependyma of the rat third ventricle following operative leakage of cerebrospinal fluid.

The role of the ventricular ependyma in the elaboration of cerebrospinal fluid under resting conditions is well documented. In an attempt to elucidate its response to cerebrospinal fluid leakage, male young adult Wistar rats were subjected to lumbar spinal transection under intraperitoneal Nembutal anaesthesia. Control animals received a sham operation, involving opening up the cerebrospinal fluid space and its closure. A scanning electron microscopical study of the third ventricular ependyma on the seventh postoperative day revealed pronounced surface modifications in the experimental animal which included (i) bulbous dilatations in the ciliary shafts with frequent apical blebbing, and an overall turgid appearance of most cilia; (ii) a profusion of tall and stout microvilli in the non-ciliated zones; (iii) an increase in the size and number of blebs; and (iv) a greater number of supraependymal cells especially on the ventricular floor. The significance of these changes is discussed in the light of available studies. The results, considered collectively, seem to reflect an augmented activity of the ventricular ependyma as a compensatory measure to counteract the effects of cerebrospinal fluid leakage caused by surgical trauma. Such activity may be both absorptive and secretory in nature.

Animals↗

PubMed1979

[Ultrastructural signs of the absorption of substances by the ependyma of the III ventricle in rats in the perinatal period].

The distribution of pinocytic vesicles, relief of apical surface and intercellular contacts were studied by means of electron microscope in ependyma of ventral region of III ventricle during perinatal period in rats. Morphological evidence was obtained for the fact that substances are absorbed by ependyma via pinocytic vesicles from the liquor beginning at least from the 16th day of prenatal development. During the postnatal period the intensity of absorption in the ventrolateral region of infundibulum of III ventricle and along the periphery of its extended part is higher than in the ventral region. At the same time the number of evaginations of the apical surface increases, especially in the ventrolateral region of infundibulum and along the periphery of its extended part. As a result, numerous depressions are formed on the ependyma surface, thus creating favourable conditions for the absorption of substances, circulating in the liquor. Changes in the apical surface configuration is provided by a special system of filaments. The apical parts of cells during perinatal period are girdled by a zone of specialized contacts, including cleft contacts, zones of adhesion and zones of closure. The latter, as known, limit markedly the penetration of substances.

Absorption↗

PubMed1979

Changes in the surface fine structure of rat third ventricular ependyma following chronic acetazolamide treatment.

Participation of non-choroidal elements, particularly of ventricular ependyma, in CSF production is well recognized. The present investigation is an attempt to elucidate possible surface changes in the ventricular lining following chronic acetazolamide administration in the rat. A progressive time-dependent change was observed in the ependyma of the third ventricle. In the dorsal ciliated zone the appearance of dilatations and surface evaginations on cilial shafts were the predominent features. The ventral non-cilated area was characterized by eruption of blebs and microvilli with apical swellings. The significance of these surface fine structural changes are discussed in the light of available studies. It appears that the ependyma is stimulated into increased activity. However, the precise nature of such a response--whether secretory or absorptive--must remain conjectural until correlative scanning and transmission electron microscopic data become available.

Acetazolamide↗

PubMed1984

Response of ependyma of the rat third ventricle to operative loss of cerebrospinal fluid: a transmission electron microscopical study.

The ependyma of the cerebral ventricles has been implicated in absorption and secretion of cerebrospinal fluid under resting and experimental conditions by various workers. To investigate the response of the ventricular ependyma to experimental leakage of the fluid, spinal transection was carried out in young adult Wistar rats in the lumbar region. The ependyma of the third ventricle was processed for transmission electron microscopy on the 7th post-operative day. The ependymal cells in the sham-operated control animal exhibited regional variations in respect of cilia, microvilli and in their relationship to the subjacent subependymal zone. However, most cells showed apical mitochondria and Golgi cisternae with few profiles of granular and smooth endoplasmic reticulum. Pinocytotic and dense-coated vesicles were not prominent features. In the operated rat, a few ultrastructural changes were noted. A profusion of microvilli and blebs with secondary surface modifications was characteristically seen on the ventricular face. Pinocytotic and dense-coated vesicles appeared to be consistent features. Proliferation of mitochondria, Golgi cisternae, polyribosomes and of smooth and granular endoplasmic reticulum was evident throughout the cytoplasm. The mitochondria, in many cases, presented a pleomorphic appearance with increased electron density. The above modifications in the fine structure, considered collectively, point to an increased ependymal activity. The evidences of both absorptive (presence of microvilli, pinocytotic and dense-coated vesicles) and secretory features (presence of blebs, proliferation in membrane components and in polyribosomes) within the same cell suggest its simultaneous involvement in both absorption and secretion. The observed changes may be interpreted as a compensatory attempt by the ependymal cell toward conservation and replenishment of cerebrospinal fluid.

Animals↗

PubMed1980

[Types of 3d cerebral ventricle ependyma in sheep and their localization using segment analysis].

Attention was focused to the determination of the topographical locality of different ependyma types and determination of their extent by the method of segment analysis. Brain samples of five sheep of the Slovak Merino breed were studied. Excised brains were transversally cut into segments from the frontal pole at 5mm intervals. The eighth, ninth and tenth slices were cast in paraffin and were cut in simultaneous series at 300 microns intervals, the cutting thickness being 10 microns. The paraffin slices were stained with haematoxylin-eosine, Gömöri's chromium haematoxylin, and by the aldehyde fuchsine method after Gömöri. Nine types of ependymal epithelium of the third cerebral ventricle were observed, according to the kind and arrangement of cells. Remarkable differences were found in the occurrence of the types of cells and in their arrangement in the ependyma at the level of the arch of the side walls and bottom of the ventricle within each segment and within the extent of the studied transversal cuts. From the viewpoint of the regulation of hypophysial functions, a significant difference exists in the structure and organization of ependyma at the locality of recessus supraopticus, recessus infundibularis and recessus mammillaris. The results of our study are in agreement with findings in laboratory animals and enrich our previous findings.

Animals↗