This study was undertaken to investigate the ultrastructure of the neurons, neuroglial cells and capillaries in the area postrema[AP] of the Oriental discolured bat, Vespertilio superans. The AP of the bat was a single midline structure at the most caudal portion of the fourth ventricle. Most neurons in the AP were small cells, but their ultrastructure were similar to the typical neurons located elsewhere in the central nervous system. Astroglial cells and oligodendrocytes were also observed and showed their typical ultrastructure. Ultrastructural features of neurons, astroglial cells and oligodendrocytes were not changed during hibernating cycles. However, microglial cells were only found in the hibernating AP ; these cells were located in the parenchyma and near the blood vessels of the AP. Since the microglial cytoplasm was filled with phagocytotic inclusions, the nuclei of the these cells were eccentrically located. Phagocytotic cytoplasmic inclusions were shown to be composed of a dense irregular peripheral region and the pale round central region. A Large vacant space was often found in the electron lucent central region. Continuous and fenestrated capillaries surrounded by pericytes were found in the bat`s AP. Especially, Phagocytotic inclusions were found in the pericyte cytoplasm of the hibernating AP, and this result supports suggestion that pericytes might be phagocytotic cells. On the basis of the distributions of phagocytotic tells[pericytes and microglial cell], ultrastructure of these cells, morphology of their cytoplasmic inclusions, and the appearance of phagocytotic activity of the pericytes during the hibernating stage when microglial cells were observed, it can be concluded that pericytes may also participates in the formation of rrlicroglial cells. Tanycytes were also found in the bat AP.
Area Postrema* ; Blood Vessels ; Capillaries ; Central Nervous System ; Cytoplasm ; Ependymoglial Cells ; Fourth Ventricle ; Inclusion Bodies ; Microglia ; Neuroglia ; Neurons ; Oligodendroglia ; Pericytes

Glial cells in the central nervous system (CNS) are composed of oligodendrocytes, astrocytes and microglia. They contribute more than half of the total cells of the CNS, and are essential for neural development and functioning. Studies on the fate specification, differentiation, and functional diversification of glial cells mainly rely on the proper use of cell- or stage-specific molecular markers. However, as cellular markers often exhibit different specificity and sensitivity, careful consideration must be given prior to their application to avoid possible confusion. Here, we provide an updated overview of a list of well-established immunological markers for the labeling of central glia, and discuss the cell-type specificity and stage dependency of their expression.
Neuroglia/metabolism* ; Central Nervous System ; Oligodendroglia/metabolism* ; Astrocytes/metabolism* ; Microglia

Glial cells, consisting of astrocytes, oligodendrocyte lineage cells, and microglia, account for >50% of the total number of cells in the mammalian brain. They play key roles in the modulation of various brain activities under physiological and pathological conditions. Although the typical morphological features and characteristic functions of these cells are well described, the organization of interconnections of the different glial cell populations and their impact on the healthy and diseased brain is not completely understood. Understanding these processes remains a profound challenge. Accumulating evidence suggests that glial cells can form highly complex interconnections with each other. The astroglial network has been well described. Oligodendrocytes and microglia may also contribute to the formation of glial networks under various circumstances. In this review, we discuss the structure and function of glial networks and their pathological relevance to central nervous system diseases. We also highlight opportunities for future research on the glial connectome.
Animals ; Neuroglia/physiology* ; Neurons/physiology* ; Astrocytes ; Microglia/physiology* ; Oligodendroglia ; Mammals

Neuroglial cells are actively participate in the pathogenesis or in the recovery procedures following brain lesions. The study was performed to evaluate the plasticity of glial cells following different degree of brain lesions. Neurosurgical operations were made on the rats fixed on the stereotaxic apparatus. Tissue column of 3 mm-diameter was isolated in the caudatoputamen with concomitant severe bleeding in the first group. In the second group, the sensorimotor cortex was suctioned out with moderate bleeding. In the third group, the mammillary body was electrically coagulated with minimal bleeding. Caudatoputamens, as a lesioned tissue or as a target tissue of lesioned area, were studied light and electron microscopically. Observations on reactivities and plasticities of neuroglial cells on the different situations, the following results were obtained : 1. Astrocytes were swollen within an hour following brain lesions. 2. In case of smaller lesion, astroglia alone remove altered structures. 3. Microglia are increased in number, if the lesion is large with severe bleeding. The microglia might come from blood monocyte via transformation to pericyte. 4. In large lesion, astroglia were greatly hypertropied, and microglia might be moving and functioning effeciently within the hypertropied cytoplasm of astroglia. 5. In the stabilizing stage, astroglia produce glial fibers and fix the exhausted microglia. Fixed microglia are proceed into apoptotic process in the cytoplasm of astroglia and removed by them. All these procedures might be controlled by various receptors and secretions of astroglia. It means that astroglia is not only the basic supporting element of nervous tissue, but also an actively functioning element for the most effective homeostatic functioning of the neuropil.
Animals ; Apoptosis ; Astrocytes ; Brain* ; Cytoplasm ; Hemorrhage ; Mamillary Bodies ; Microglia ; Monocytes ; Neuroglia* ; Neuropil ; Pericytes ; Plastics* ; Rats ; Suction

In the past decade, structural, molecular, and functional changes in glial cells have become a major focus in the search for the neurobiological foundations of schizophrenia. Glial cells, consisting of oligodendrocytes, astrocytes, microglia, and nerve/glial antigen 2-positive cells, constitute a major cell population in the central nervous system. There is accumulating evidence of reduced numbers of oligodendrocytes and altered expression of myelin/oligodendrocyte-related genes that might explain the white matter abnormalities and altered inter- and intra-hemispheric connectivities that are characteristic signs of schizophrenia. Astrocytes play a key role in the synaptic metabolism of neurotransmitters ; thus, astrocyte dysfunction may contribute to certain aspects of altered neurotransmission in schizophrenia. Increased densities of microglial cells and aberrant expression of microglia-related surface markers in schizophrenia suggest that immunological/inflammatory factors are of considerable relevance to the pathophysiology of psychosis. This review describes current evidence for the multifaceted role of glial cells in schizophrenia and discusses efforts to develop glia-directed therapies for the treatment of the disease.
Astrocytes ; Central Nervous System ; Foundations ; Metabolism ; Microglia ; Neuroglia* ; Neurotransmitter Agents ; Oligodendroglia ; Psychotic Disorders ; Schizophrenia* ; Synaptic Transmission

OBJECTIVES: Retinopathy of prematurity (ROP) is one of the major cause of vision loss among children. Recently, the prevalence of ROP is markedly increasing as the survival rate of very-low-birth-weight premature infants has been improved. It is widely accepted that retinal hypoxia results in the release of factors influencing new blood vessel growth. But, it is little known about the morphological changes of retinal astrocytes and Muller cells in the ROP model. So, we planned to investigate the morphological changes of those retinal glial cells induced by alternating hyperoxic and hypoxic injury in ROP. METHODS: Newborn rats (postnatal day 6) were exposed to two different oxygen concentrations alternating every 24 hours until postnatal day 14. Used oxygen concentrations were 10~15% for hypoxic episode and 55~80% for hyperoxic episode. Afterthen, they were returned to room air. A group of animal served as a room air control. Retinal vascularity was assessed by ADPase reaction and morphology of retinal glial cells was observed using transmisson electron microscope. RESULTS: Preretinal neovascular tufts were observed in 2 out of 12 animals of group III (75/10%) and 4 out of 12 animals of group IV (80/10%), respectively. There was no remarkable structural change of astrocytes. But we could observe some morphological changes of Muller cells. Retraction of the radial processes of Muller cells and breaking of basal lamina were noted at the site of preretinal neovascularization. Decrease in the space occupied by the cytoplasmic processes of Muller cells was observed in the inner nuclear layer of group IV retinae. Infiltration of microglia or macrophage into the vitreo-retinal interface and the site of extravasation was noted. Findings suggestive of neuronal cell death were also observed especially in the inner nuclear layer. CONCLUSIONS: Morphological change of Muller cells and resultant loss of integrity of internal limiting membrane seemed to be the most important step for preretinal neovascularization. But, no structural changes of astrocytes were noted.
Animals ; Anoxia ; Apyrase ; Astrocytes* ; Basement Membrane ; Blood Vessels ; Cell Death ; Child ; Cytoplasm ; Ependymoglial Cells* ; Humans ; Infant, Newborn ; Infant, Premature ; Macrophages ; Membranes ; Microglia ; Models, Animal* ; Neuroglia ; Neurons ; Oxygen ; Prevalence ; Rats* ; Retina ; Retinaldehyde ; Retinopathy of Prematurity* ; Survival Rate

Spinal cord injuries are damages that result in complete or partial loss of sensation and/or mobility and affect the life qualities of many patients. Their pathophysiology includes primary and secondary processes, which are related with the activation of astrocytes and microgliacytes and the degeneration of oligodendrocytes. Although transplantation of embryonic stem cells or neural progenitor cells is an attractive strategy for repair of the injured central nervous system (CNS), transplantation of these cells alone for acute spinal cord injuries has not resulted in robust axon regeneration beyond the injury sites. This may be due to the progenitor cells differentiating to the cell types that support axon growth poorly and/or their inability to modify the inhibitory environment of adult CNS after injury. Recent studies indicate that transplantation of glial progenitor cells has exhibited beneficial effects on the recovery and promising future for the therapy strategy of spinal cord injury. In this review, we summarized the data from recent literature regarding glial implications in transplantation therapy of spinal cord injury.
Animals ; Astrocytes ; transplantation ; Humans ; Microglia ; transplantation ; Neuroglia ; physiology ; transplantation ; Oligodendroglia ; transplantation ; Spinal Cord Injuries ; surgery ; Stem Cell Transplantation

NG2-glia are a major type of glial cells that are widely distributed in the central nervous system (CNS). Under physiological conditions, they mainly differentiate into oligodendrocytes and contribute to the myelination of axons, so they are generally called oligodendrocyte progenitor cells. Emerging evidence suggests that NG2-glia not only act as the precursors of oligodendrocytes but also possess many other biological properties and functions. For example, NG2-glia can form synapse with neurons and participate in energy metabolism and immune regulation. Under pathological conditions, NG2-glia can also differentiate into astrocytes, Schwann cells and even neurons, which are involved in CNS injury and repair. Therefore, a deeper understanding of the biological characteristics and functions of NG2-glia under physiological and pathological conditions will be helpful for the treatment of CNS injury and disease. This article reviews the recent advances in the biological characteristics and functions of NG2-glia.
Astrocytes ; Central Nervous System ; Neuroglia ; Neurons ; Oligodendroglia

GFAP (Glial Fibrillary Acidic Protein) was one of the intermediate filament group and used as an astrocyte marker. The numerous studies about GFAP immunoreactive cell's distribution were investigated for fetus, neonate and aged brains. There are several reports about that GFAP immunoreactive cells were appeared at early fetus and after birth. In cases of mammalian fetus radial glia cells migrated toward pial surface at early stage and revealed GFAP immunoreactivity by the immunostain. But in cases of rodents, they migrated at late gestation or after birth. This study, the GFAP immunoreactive cells' localizations and distribution in the fetuses (the 30 th, 45 th, 60 th, 90 th, 105 th, 120 th of gestation) and neonate mesencephalon of korean native goat were investigated by immunohistoche-mistry (ABC method). The results obtained in this study were summarized as followings; 1. Multipolar astrocytes at 60 days of gestation were found in midbrain, in 90 days of gestation were found in cerebral aqueduct. 2. Radial glial cell presented 60 days of gestation and process of GFAP immunoreaction was to stretch out from ventricular to pia mater and nonpolar immunoreactive cell was transformed to bipolar, monopolar and multipolar immunoreactive cell. 3. The number of GFAP immunoreactive cells of field were gradually decreased from 90 days of gestation till 105 days of gestation. But in 120 days of gestation and newborn were slightly increased. 4. Immunoreactivity of GFAP immunoreactive cells were gradually decreased from 95 days of gestation till 120 days of gestatioin. These results were suggested that radial glial cell of midbrain developed very earlier than that of cerebral aqueduct. However, cerebral aqueduct developed lately than that of midbrain, but faster developing than other.
Astrocytes ; Brain ; Cerebral Aqueduct ; Ependymoglial Cells ; Fetus* ; Goats* ; Humans ; Infant, Newborn* ; Intermediate Filaments ; Mesencephalon* ; Neuroglia ; Parturition ; Pia Mater ; Pregnancy ; Rodentia

Toll-like receptors (TLRs) belong to a class of pattern recognition receptors that play an important role in host defense against pathogens. TLRs on innate immune cells recognize a wide variety of pathogen-associated molecular patterns (PAMPs) and trigger innate immune responses. Later, it was revealed that the same receptors are also utilized to detect tissue damage to trigger inflammatory responses in the context of non-infectious inflammation. In the nervous system, different members of the TLR family are expressed on glial cells including astrocytes, microglia, oligodendrocytes, and Schwann cells, implicating their putative role in innate/inflammatory responses in the nervous system. In this regard, we have investigated the function of TLRs in neuroinflammation. We discovered that a specific member of the TLR family, namely TLR2, functions as a master sentry receptor to detect neuronal cell death and tissue damage in many different neurological conditions including nerve transection injury, intracerebral hemorrhage, traumatic brain injury, and hippocampal excitotoxicity. In this review, we have summarized our research for the last decade on the role of TLR2 in neuroinflammation in the above neurological disorders. Our data suggest that TLR2 can be an efficient target to regulate unwanted inflammatory response in these neurological conditions.
Astrocytes ; Brain Injuries ; Cell Death ; Cerebral Hemorrhage ; Cerebral Hemorrhage, Traumatic ; Humans ; Immunity, Innate ; Inflammation ; Microglia ; Nervous System ; Nervous System Diseases ; Neuralgia ; Neurodegenerative Diseases* ; Neuroglia ; Neurons ; Oligodendroglia ; Receptors, Pattern Recognition ; Schwann Cells ; Stroke ; Toll-Like Receptors