Brain-Region Specific Apoptosis Triggered by Eph/ephrin Signaling

Eph receptors and their ligands, ephrins, are abundantly expressed in neuroepithelial cells of the early embryonic brain. Overstimulation of Eph signaling in vivo increases apoptotic cell death of neuroepithelial cells, whereas null mutation of the Eph gene leads to the development of a larger brain during embryogenesis. Thus, it appears that Eph-ephrin signaling plays a role in regulating apoptotic cell death of neuroepithelial cells, thereby influencing brain size during embryonic development. Interestingly, Eph-ephrin signaling is bi-directional, with forward signaling from ephrin- to Eph-expressing cells and reverse signaling from Eph- to ephrin-expressing cells. However, it is not clear whether this forward or reverse signaling plays a role in regulating the size of the neuroepithelial cell population during early brain development. Also, Eph receptors and their corresponding ligands are mutually exclusive in their expression domains, and they encounter each other only at interfaces between their expression domains. This expression pattern may be a critical mechanism for preventing overstimulation of Eph-ephrin signaling. Nevertheless, Eph receptors are co-expressed with their corresponding ligands in certain brain regions. Recently, two studies demonstrated that brain region-specific apoptosis may be triggered by the overlapping expression of Eph and ephrin, a theme that will be explored in this mini-review.

Diffuse Ependymal Dysembryoplastic Neuroepithelial Tumor Causing Spinal Drop Metastases: A Case Report

Dysembryoplastic neuroepithelial tumors (DNETs) arise mostly in the supratentorial cerebral cortex. A very rare case of intraventricular DNET with diffuse ependymal involvement, which causes spinal drop metastasis, is presented.

Changes in the Histone Acetylation Patterns during the Development of the Nervous System

Epigenetic modification such as DNA methylation and histone acetylation plays essential roles in many aspects of cellular function and development of animals. There is an increasing amounts of evidence for dynamic changes in the histone acetylation of specific gene segments, but little attempt was made to examine global pattern changes in the histone acetylation in developing nervous system. In this study, we found that acetylated histone H3 and H4 immunoreactivities were relatively weak in neuroepithelial cells in the ventricular zone of developing rat cerebral cortex or chick spinal cord, compared to the immature young neurons in the cortical plate of a rat embryo or lateral motor column in chick spinal cord. On the other hand, adult neural stem cells in the dentate gyrus (DG) of rat hippocampal formation did not exhibit such diminished histone acetylation, compared to neuroblasts and mature DG neurons. These results suggest that the level of histone acetylation is highly dynamic and tightly linked to the neuronal types and the differentiation stages.

study on in-vitro transdifferentiation of rat bone marrow stromal cells into neuroepithelial-like cells

Bone marrow stem cells [BMSCs] are a rich source of stem cells and may represent a valid alternative to neural or embryonic stem cells by replacing the autologous damaged tissues in neurodegenerative diseases. In this study, we attempted to devise a protocol for the induction of BMSCs into neuroepithelial-like cells [NELCs]. Rat BMSCs were isolated from the long bones of adult Sprague-Dawley rats. Their purity in the 4th passage was evaluated with fibronectin by immunocytochemistry, and the stemness marker Oct-4 was assessed by RT-PCR technique. The cells were expanded and induced in the induction stage. The BMSCs were incubated with either beta-mercaptoethanol [micro ME] [1 mM], dimethyl sulfoxide [DMSO] [2%] or biotylated hydroxyanisol or butylated hydroxyanisol [BHA] [200 micro M] in beta-MEM medium without fetal bovine serum [FBS]. They were washed with phosphate buffer saline [PBS] and proceeded to the 2nd phase of induction, where the induction medium was changed with beta-MEM and 15% FBS containing all-trans retinoic acid [RA] [1 micro M] [for 3 days]. Then, the expression of the markers was assessed with GFAP, nestin and neurofilament 68 antibodies, respectively and the expression of Oct-4 and NeuroD was evaluated by RT-PCR. The purity of the BMSCs at the 4th passage was more than 92%. The mRNA of Oct-4 was expressed in these cells. Induction of BMSCs by DMSO-RA could differentiate NELCs significantly more than beta ME-RA and BHA-RA. The transdifferentiation of NELCs was evaluated by nestin antibody and NeuroD mRNA expression; later markers expressed very low detectable level in BMSCs. But the differentiation of BMSCs into astrocytes was less in all of the experiment groups that is estimated GFAP antibody. The application of DMSO-RA can transdifferentiate BMSCs into NELCs in- vitro

[ Study on Transdifferentiation of Bone Marrow Stromal Cells into Neuronal and Glial-Like Cells In Vitro by Different Inducers]

There are some evidences to suggest that bone marrow stromal cells [BMSCs] not only differentiate into mesodermal cells, but also adopt the fate of endodermal and ectodermal cell types. BMSCs can be a valuable cell source as an autograft for clinical application involving regeneration of the central nervous system. Bone marrow stromal cells can he expanded rapidly in vitro and can he differentiat into neuronal- and glial-like cells. In this study, we attempted to devise a protocol or protocals for the induction of BMSCS into neuroepithelial- and neuroglial-like cells. Bone marrow was extracted from the femur and tibia of adult rat, and then bone marrow stromal cells with 4 passages were proliferated and cultured and then were evaluated with fibronectin by immunocytochemistry and Oct-4 by semi quantitative RT-PCR techniqucs. Also in this stage expression of Nestin. NF68, GFAP and 04 antibodies respectively markers of neuroepithelia1, neuron astrocytes and oligodendrocytes cells, were assessed. Rat BMSCs were differentiatec; by two consequent indductors into neuroepithelial. neuronal and glial-like cells. At pre-induction stage dimethyl sulfoxide [DMSO], beta-mercaptoethanol [[3ME] or biotylated hydroxyanisol [BHA] were separattly and without fetal bovine serum [betaBS] addled to alpha minimal essential medium [alfa-MEM], and then a induction stage medium was replaced by retinoic acid [RA] and 15% FBS in alfa-MEM. Four days later, expressions of neuronal and glial markers were assessed. In addition, expression of NeuroD and Oct-4 mRNA were assessed in these cells. More than 92% of BMSCs was fibronectin positive at passage 4. A few percent of BMSCs differentiated into neuroepithelial and neuron-like cells but no astrocyte and oligoclendiocyte-like cell were detected. Oct-4 mRNA was highly expressed in these cells while NeuroD mRNA expression was not detected Induction of BMSCs by DMSO-RA differentiated BMSCs into neuroepithelial and neuronal-like cell significantly compare to betaME-RA and BHA-RA. Transdifferentiation of the treated BMSCs into astrocytes and oligodendrocyte-like cells was less than 5%. Indluction of BMSCs by DMSO-RA resulted in expression of NeuroD niRNA but Oct-4 mRNA was not expressed in none of treatment groups. Induction of BMSCs by different inducers specially DMSO-RA could highly transdifferentiate BMSCs into neuroepithelial and neuronal-like cells, whereas glial-like cells transdifiŠrentiation was very low

Spinal intramedullary neuroepithelial (ependymal) cyst. A rare cause of treatable acute para paresis.

An 8-yr-old female child presented with acute onset of severe pain in the lower limbs and difficulty in walking. Spine MRI showed hyperintense signals on T2 weighted images at T2-T3 level, which was intramedullary in location. The patient was operated and histopathology reported as neuroepithelial cyst. Spinal intramedullary neuroepithelial cysts are rare. Spinal cord compression due to the cyst is very uncommon and because of its rarity the present case is being reported. The clinical features, embryogenesis and literature were reviewed briefly.

Differentiation and Regeneration of Olfactory Neuroepithelial Cells / 대한이비인후과학회지

No abstract available.

Immature Teratoma of the Nasal Cavity / 대한이비인후과학회지

Teratomas are embryonal neoplasms that show characteristics from all three germ layers(ectoderm, endoderm, and mesoderm). These tumors are frequently present in infancy and childhood. Teratomas are classified into three groups : mature teratoma, immature teratoma, and teratomas with malignant elements. The histopathologic findings of immature teratoma is primitive neuroepithelial cells compounding pseudostratified tubular formations. The pure immature teratoma accounts for fewer than 1% of all germ cell malignancies. The immature teratomas in nasal cavity are very rare tumor. These tumors are often presented as neonatal respiratory distress, nasal obstruction and epistaxis. We report a case of histologically confirmed immature teratoma in nasal cavity in 48 years old man with review of the literature.

Experimental Study on the Effects of Cabarmazepine on the Neurulation in Early Chick Embryos and Immunohistochemical Staining for Fibronectin

Teratogenic effects of carbamazepine, an anticonvulsant, on the neurulation of the explanted early chick embryos were studied utilizing the punched-out filter paper explantation and culture technique. Fresh fertilized white leghorn hen eggs were incubated for 20-30 hours in an egg incubator. The Hamburger and Hamilton stage 4-11 chick embryos were explanted using the punched-out filter paper explantation technique and cultured in the CO2 cell culture incubator for 6-10 hours. They were randomly divided into a control group and an experimental group. The experimental group was divided into five subgroups according to the carbamazepine concentrations of 20micrometer 40micrometer 100micrometer 200micrometer 400micrometer with which the Ham's F-10 culture media were treated. The morphological characteristics and the incidences of teratogenic effects on the neurulation of early chick embryos in the control and experimental groups were compared with each other using the stereomicroscope and the electron microscope. The chick embryos of the same developmental stage were selected from the control and experimental groups, and immunohistochemical staining for fibronectin was done by the double-bridge PAP method. The results were as follows. 1) Of the 41 chick embryos cultured in the Ham's F-10 media without carbamazepine, 38 embryos(92.7%) developed normally, and 3 embryos(7.3%) developed abnormally. In contrast, among the 98 embryos cultured in the carbamazepine-treated media, 54 embryos(55.1%) developed abnormally. The frequent anomalous features were deformities of the neural folds, failure of neural tube closure, derangement of somites, and developmental arrest. 2) The frequency and severity of abnormal embryos increased in dose-dependent fashion. The embryos cultured in the media treated each with 20micrometer 40micrometer 100micrometer 200micrometer 400micrometer of carbamazepine developed abnormally in 12.5%, 21.1%, 60.0%, 81.0%, 86.4% respectively. 3) The scanning electron microscopic findings in neuroepithelial cells of abnormally developed embryos were flattened and smooth cellular surface with diminished surface blebs and microvilli, and size irregularity of the cells. On transmission electron microscope, underdevelopment of intracellular microfilaments was seen, but there was no significant change in the intracellular organelle. 4) The immunohistochemical stainability of the extracellular fibronectin at the basal side of the neuroepithelium was decreased in the carbamazepine-treated embryos.

effects of electromagnetic fields on some neuroepithelial structures in the inner ear of rats

This work was dedicated to study the effects of long term exposure to time varying extremely low frequency electromagnetic fields on some neuroepithelial structures in the inner ear of rats. This work was conducted on 15 male adult albino rats, 5 rats were sham exposed and served as normal controls and 10 rats were exposed to time varying electromagnetic field of extremely low frequency [50 Hz] and 10-mT flux density for one hour daily, for 30 days. By the end of the experiment animals were anesthetized, perfused with the proper fixative then decapitated. The inner ears were reperfused and the temporal bones obtained. The specimens were put in a decalcifying agent for about 5 days. The specimens were prepared for either histological or scanning electron microscopical study. The present study revealed histological changes in all experimental specimens examined. The cochlea showed variable degrees of affection ranging from of cytoplasmic vacuolation of some supporting cells, to complete destruction of the organ of Corti. Stria vascularis showed atrophied lining cells. Spiral ganglionic cells appeared swollen with karyolitic nuclei. Vestibular neuroepithelial structures revealed milder response in the form of cytoplasmic vacuolation of both hair cells and supporting cells. From the previous results it could be concluded that long-term exposure to 10-mT extremely low frequency time varying electromagnetic field caused degenerative changes in the neuroepithelial structures of rat's inner ear

Ultrastructural Changes in the Neurulation of Early Chick Embryos Treated with Diphenylhydantoin

Teratogenic effects of a diphenylhydantoin on the neurulation of the explanted early chick embryos were studied using the punched-out filter paper explantation technique. The 6th to 9th Hamburger and Hamilton staged chick embryos were explanted and cultured in the Ham's F-10 media treated with 15 microgram/ml, 30 microgram/ml, 60 microgram/ml, 90 microgram/ml, 120 microgram/ml of diphenylhydantoin in the CO2 incubator for 6-9 hours. The morphological chracteristics and the ultrastructural changes of the neuroepithelium of early chick embryos were compared with the control and experimental group using the stereomicroscope and the electron microscope. Of th 40 chick embryos cultured in the Ham's F-10 media without drug, 37 embryos(92.5%) developed normally and 3 embryos(7.5%) developed abnormally in 94 embryos(61.4%). The frequent anomalous features of the embryos were deformities of the neural folds in the cranial regions, failure of neural tube closure, dispersion of somites and developmental arrest. The scanning electron microscopic findings of neuropithelial cells of abnormally developed embryos were diminished surface blebs and microvilli, flattened and smooth cellular surfaces, and irregular size of cells. The transmission electron microscopic findings of neuroepithelial cells of abnormally developed embryos showed no significant changes of the development of intracellular organelles except the smooth cellular surface and mild underdevelopment of microfilaments.