Neural Stem Cells and Oligodendrocyte Progenitors in the Central Nervous System
Richard K. Burt, Alberto M. Marmont in Stem Cell Therapy for Autoimmune Disease, 2019
Glial cells constitute the majority of the cells in the CNS. These cells provide the structural scaffolding that is important for migration of early neuroblasts, are a major source of adhesion molecules that participate in the formation of neural networks, form limiting membranes that separate the CNS from other tissues and aid in the rapid conduction of electrical impulses down axons of mature neurons. There is now growing recognition that glia, possibly through their immense glial networks, may possess communication skills that complement those of neurons themselves.1,2 Astroglia are stellate, branched supporting cells that contact the soma, dendrites and axons of neurons, the soma and processes of oligodendrocytes and associate intricately with other astrocytes. Their close association with the surface of various neurons is thought to mediate the exchange of substances between these two cell types.3 Their multiple processes also contact, induce and maintain the tight junctions in endothelial cells that effectively form the blood-brain barrier. Oligodendroglia, also a supporting glial cell type present in the CNS, extend many processes, each of which contacts and repeatedly envelopes a stretch of axon with subsequent condensation of its spiraling plasma membrane. This myelination of axons imparts insulating properties that allow the rapid propagation of action potentials throughout the CNS without continuous regeneration of the action potential along each segment of an axon.
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Oligodendroglia (from Greek, oligos: few; dendron: tree, glia: glue): these are the glial cells that produce MYELIN within the CNS. OLIGODENDROGLIA (or oligodendrocytes as they are also known) come in four basic types, though there appear also to be some transition forms. These are type I (spherical cell bodies, many processes: found at many levels of the CNS, often associated with blood vessels or fibre pathways); type II (more cuboid than spherical and with fewer processes than type I; only found in white matter); type III (three or four processes only: found in the CEREBELLUM, CEREBRAL PEDUNCLES and CEREBELLAR PEDUNCLES, MEDULLA OBLONGATA and SPINAL CORD); and type IV (associated with the points of entry of CRANIAL NERVES into the CNS: these oligodendroglia are the most similar to Schwann cells). The function of oligodendroglia is to provide myelin to central nervous system neurons: myelin functions as an electrical insulator of axons, speeding axonal conduction velocities. A single oligodendrocyte will provide myelin for more than one neuron (and one neuron will be myelinated by more than one oligodendrocyte). The processes of myelination involves the processes of oligodendrocytes making contact with an axon and then wrapping around it in a spiral fashion. The process of myelination in humans can take very many years: it is not generally completed until individuals are in their mid-teenage years. Myelin can be visualized in the CNS by various histological techniques (see HISTOLOGY; CHEMICAL NEUROANATOMY) but the most effective is the GALLYAS SILVER stain for myelin.
Brain Development and Its Relationship to Patterns of Injury
Richard A. Jonas, Jane W. Newburger, Joseph J. Volpe, John W. Kirklin in Brain Injury and Pediatric Cardiac Surgery, 2019
The panorama of brain development follows complicated developmental programs. Figure 2-1 illustrates patterns of brain development showing the relationship between neurogenesis, gliogenesis, synaptogenesis, and development of white matter.4 Much of the neurogenesis in the brain has been completed by the time of full-term birth in the human (Figure 2-1). Major anomalies in the primitive neural tube, such as spina bifida, occur well before birth at approximately 30 days gestation. During the period of infancy from birth through the first year, when cardiac surgery is frequently undertaken, the major developmental events include completion of neuronal migration into areas such as the cerebellum and glial multiplication. Some of these glia are the oligodendroglia, which form myelin to cover transcortical tracts in the brain itself. Myelination is initiated in the brain stem and continues beyond 20 years of age in the commissures in the cerebral hemispheres and deep frontal lobe white matter. Developing myelin is very vulnerable to ischemic injury, especially before 32 weeks gestation.5
Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma
Published in Ultrastructural Pathology, 2020
Evgeniya Yu. Kirichenko, Sehweil Salah M. M., Zoya A. Goncharova, Aleksei G. Nikitin, Svetlana Yu. Filippova, Sergey S. Todorov, Marina A. Akimenko, Alexander K. Logvinov
Despite the rarity of PXA, a large amount of data concerning the features of the cellular structure of this type of tumor has been accumulated. Nevertheless, the characteristics of intercellular communication in PXA are poorly studied. To date, only a few descriptions of desmosome-like contacts have been obtained.11,12 At the same time, the existence of gap junctions and half-channels, as well as the expression of their constituent proteins in astrocytic tumors, is an urgent topic in modern neurooncology.13–15 Gap junctions (GJ) are hexametric membrane pores, formed by connexins that directly connect cytoplasms of two cells. In nervous tissue, they can be formed either between neuronal cells16, or between astroglial and oligodendroglial cells.17 According to the modern data, GJs occupy a special place among the various types of intercellular contacts and serve as the key structural and functional component of metabolic homeostasis maintenance in the brain.18 The controversial role of GJ in astrocytic tumor pathogenesis has been investigated in a number of studies. On the one hand, GJ possesses such pro-oncogenic properties as tumor cells migration promotion19 and transmission of transforming signals from tumor to nonmalignant tissue.20 On the other hand, connexins proteins have been known for the antiproliferative activity.14
Maternal psychosocial stress during early gestation impairs fetal structural brain development in sheep
Published in Stress, 2020
Markus Hermes, Iwa Antonow-Schlorke, Dorothea Hollstein, Sarah Kuehnel, Florian Rakers, Vilmar Frauendorf, Michelle Dreiling, Sven Rupprecht, Harald Schubert, Otto W. Witte, Matthias Schwab
Parallel to the altered network formation after MPS during the first and second trimester, we demonstrated decreased myelination and proliferative cell activity specifically in the subcortical and deep white matter where myelination was most advanced. Because the stress-related decrease of MBP IR was not accompanied by a loss of axonal processes, our results point to a specific stress effect on myelination. This effect may be mediated by decreased oligodendroglial proliferation. Although we did not differentiate between neuronal and glial proliferative activity, it is highly likely that the decrease in proliferative-active cells mainly involves glial cells since glial but not neuronal proliferation peaks during the second half of gestation (Barlow, 1969; McIntosh, Baghurst, Potter, & Hetzel, 1979). The low susceptibility of the cerebral cortex to stress may be due to the later onset of cortical myelination at the end of third trimester of pregnancy (Barlow, 1969). Indeed, myelination was still very low in the cerebral cortex during the third trimester. The effects of MPS on myelination in the white matter during the first and second trimester are in general agreement with findings in rodents (Suzuki et al., 2016; Xu et al., 2013). Although rodents were exposed to mid-to-late gestational stress, the stress period resembles that in our study since mice are born very prematurely with brains at a developmental stage of 0.25 to 0.5 gestation compared to sheep and humans (Bayer, Altman, Russo, & Zhang, 1993; Darlington et al., 1999).
Neuroanniversary 2022
Published in Journal of the History of the Neurosciences, 2022
Paul Eling
Heinrich Obersteiner (1847–1922) was an Austrian neurologist born in Vienna. In 1870, he earned his doctorate from the University of Vienna, where he worked in the laboratory of Ernst Wilhelm von Brücke (1819–1892). In 1873, he earned his habilitation for pathology and anatomy of the nervous system at the University of Vienna, becoming an associate professor there in 1880 and a full professor in 1898. He was also the director of a private mental institution at Oberdöbling, outside of Vienna. In 1882, he established an internationally known neurological institute in Vienna. The eponymous Obersteiner–Redlich line is named after him and Emil Redlich (1866–1930). This zone is where the central nervous system and peripheral nervous system meet, as well as the place where Schwann cells meet oligodendroglia cells.