Neural System - Glial Development

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Introduction

Neural Development timeline
Neural Development

Within the neural tube stem cells generate the 2 major classes of cells that make the majority of the nervous system: neurons and glia. Both these classes of cells differentiate into many different types generated with highly specialized functions and shapes.


Glia (Greek, glia = "glue") and neurons have the same general embryonic origin, generated from neural tube ventricular layer stem cells and neural crest. The developmental process of glial cell development is described as gliogenesis. Glial cells have important roles in neural development and in the adult nervous system and have come a long way from their original description as "supportive cells".


Myelination is the process of close wrapping around a neural axon by a glial cell. This second process occurs as a late feature of glial and nervous system development in both the central and peripheral nervous system and has mainly been studied in relation to demyelinating diseases, such as multiple sclerosis.


Types of glia: radial glia, astroglia, oligodendroglia, microglia and Schwann cells.


Development of the neural crest and sensory systems (hearing/vision/smell) are only briefly introduced in these notes and are covered in detail in another notes sections. (More? Neural Crest | Sensory).


Neural Links: ectoderm | neural | neural crest | ventricular | sensory | Stage 22 | gliogenesis | neural fetal | Medicine Lecture - Neural | Lecture - Ectoderm | Lecture - Neural Crest | Lab - Early Neural | neural abnormalities | folic acid | iodine deficiency | Fetal Alcohol Syndrome | neural postnatal | neural examination | Histology | Historic Neural | Category:Neural

Neural Crest Development | Sensory System Development

Some Recent Findings

  • Emx2 and Foxg1 inhibit gliogenesis and promote neuronogenesis[1] " Neural stem cells (NSCs) give rise to all cell types forming the cortex: neurons, astrocytes, and oligodendrocytes. The transition from the former to the latter ones takes place via lineage-restricted progenitors in a highly regulated way."
  • A common progenitor for retinal astrocytes and oligodendrocytes[2] "Here we use retroviruses to label clones of glial cells in the chick retina. We found that almost every clone had both astrocytes and oligodendrocytes. In addition, we discovered a novel glial cell type, with features intermediate between those of astrocytes and oligodendrocytes, which we have named the diacyte. Diacytes also share a progenitor cell with both astrocytes and oligodendrocytes."
  • Neural Stem Cell Differentiation[3] "Upon evaluating distinct growth-permissive substrates in an embryonic stem cell-neurogenesis assay, we found that laminin, fibronectin, and gelatin instruct neural fate and alter the functional specification of neurons when applied at distinct stages of development." (More? Stem Cells )
More recent papers
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Search term: Glial Embryology

<pubmed limit=5>Glial Embryology</pubmed>

Radial Glia

Interneuron-radial glial interactions[4]

Radial glia were first identified in the human fetal brain using classical Golgi silver impregnation histology.[5] These cells have an important role in nervous system development, guiding newly formed neurons from their birth zone (ventricular layer) outward to their final adult position. Radial glia generate initially neurons then astrocytes after neurogenesis has been completed.[6][7]

Astroglia

Astrocytes and neonatal hypoxia ischemia.[8]

Astrocytes get their name from their cell shape, a star-like "astral" appearance.

Steindler DA, Laywell ED. Astrocytes as stem cells: nomenclature, phenotype, and translation. Glia. 2003 Jul;43(1):62-9. Review.

Scemes E, Giaume C. Astrocyte calcium waves: what they are and what they do. Glia. 2006 Nov 15;54(7):716-25. Review.

Oligodendroglia

In the early spinal cord, a ventral ventricular zone region generates oligodendrocyte precursors initially which then migrate both laterally and dorsally.

In the later spinal cord, the dorsal region provides a secondary source of oligodendrocyte precursors.

Oligodendrocyte wars. Richardson WD, Kessaris N, Pringle N. Nat Rev Neurosci. 2006 Jan;7(1):11-8. Review.

Baron W, Colognato H, ffrench-Constant C. Integrin-growth factor interactions as regulators of oligodendroglial development and function. Glia. 2005 Mar;49(4):467-79. Review.

Microglia

Glial cells that act within the central nervous system in the same role as macrophages in other body tissues and act as an innate immune system. There other role is as the cellular mediators of neuroinflammatory processes[9] and cell death[10].

Schwann cells

Schwann cell myelination and dedifferentiation[11]

These cells are named after Theodor Schwann (1810 - 1882), a German physiologist and histologist, who along with Schleiden were early developers of the "cell theory". Neural crest cells differentiate to form the glial lineage, which in turn generate Schwann cell precursors. (More? Neural Crest Development).

Schwann cells formation is regulated by at least two signals, neuregulin-1 and endothelin. Neuregulins are a family (NRG1, NRG2, NRG3, and NRG4) of EGF-like signaling molecules that bind ErbB receptor tyrosine kinase receptors. Neuregulin-1 type III is expressed on axon surface and has been shown to also regulate Schwann cell membrane growth, adjusting myelin sheath thickness to match axonal calibre.

Mouse-sciatic nerve Schwann cell.jpg

Mouse - sciatic nerve Schwann cell interaction[12]


Links: Neural Crest Development

Development Overview

Human Neuralation - Early Stages

The stages below refer to specific Carneigie stages of development.

  • stage 8 (about 18 postovulatory days) neural groove and folds are first seen
  • stage 9 the three main divisions of the brain, which are not cerebral vesicles, can be distinguished while the neural groove is still completely open.
  • stage 10 (two days later) neural folds begin to fuse near the junction between brain and spinal cord, when neural crest cells are arising mainly from the neural ectoderm
  • stage 11 (about 24 days) the rostral (or cephalic) neuropore closes within a few hours
    • closure is bidirectional
    • it takes place from the dorsal and terminal lips and may occur in several areas simultaneously
    • The two lips, however, behave differently.
  • stage 12 (about 26 days) The caudal neuropore takes a day to close
    • the level of final closure is approximately at future somitic pair 31
    • corresponds to the level of sacral vertebra 2
  • stage 13 (4 weeks) the neural tube is normally completely closed
  • Secondary neurulation begins at stage 12
    • is the differentiation of the caudal part of the neural tube from the caudal eminence (or end-bud) without the intermediate phase of a neural plate.

(Text modified from: Neurulation in the normal human embryo. O'Rahilly R, Muller F Ciba Found Symp 1994;181:70-82)

Fetal - Third Trimester

Three-dimensional magnetic resonance imaging and image-processing algorithms have been used to quantitate between 29-41 weeks volumes of: total brain, cerebral gray matter, unmyelinated white matter, myelinated, and cerebrospinal fluid (grey matter- mainly neuronal cell bodies; white matter- mainly neural processes and glia). A study of 78 premature and mature newborns showed that total brain tissue volume increased linearly over this period at a rate of 22 ml/week. Total grey matter also showed a linear increase in relative intracranial volume of approximately 1.4% or 15 ml/week. The rapid increase in total grey matter is mainly due to a fourfold increase in cortical grey matter. Quantification of extracerebral and intraventricular CSF was found to change only minimally.[13]

Neural-development.jpg

Myelination

The electron micrograph images below are selected neural tissues of adult mouse axon cross-sections surrounded by glial-derived myelin (black rings).

Links: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=bnchm&part=A244

Postnatal Neural

Neural development continues after birth with substantial growth, death and reorganization occuring during the postnatally. (More? Postnatal Development - Neural) The references below give a sample of some recent findings and research methods.

Cortex Matures Faster in Youth with Highest IQ (More? NIH - Cortex Matures Faster in Youth with Highest IQ)

  • Neural induction: old problem, new findings, yet more questions.[14] "During neural induction, the embryonic neural plate is specified and set aside from other parts of the ectoderm. A popular molecular explanation is the 'default model' of neural induction, which proposes that ectodermal cells give rise to neural plate if they receive no signals at all, while BMP activity directs them to become epidermis. However, neural induction now appears to be more complex than once thought, and can no longer be fully explained by the default model alone. This review summarizes neural induction events in different species and highlights some unanswered questions about this important developmental process."
  • Diffusion tensor imaging of neurodevelopment in children and young adults. [15] "Diffusion tensor magnetic resonance imaging (DTI) was used to study regional changes in the brain's development from childhood (8-12 years, mean 11.1 +/- 1.3, N = 32) to young adulthood (21-27 years, mean 24.4 +/- 1.8, N = 28). ..... These findings suggest a continuation of the brain's microstructural development through adolescence."

Abnormalities

Multiple Sclerosis

  • Activation of the subventricular zone in multiple sclerosis: evidence for early glial progenitors.[16] "In multiple sclerosis (MS), oligodendrocyte and myelin destruction lead to demyelination with subsequent axonal loss. Experimental demyelination in rodents has highlighted the activation of the subventricular zone (SVZ) and the involvement of progenitor cells expressing the polysialylated form of neural cell adhesion molecule (PSA-NCAM) in the repair process."

Experimental Autoimmune Encephalomyelitis

(EAE) This is an animal model of autoimmune demyelination, such as in multiple sclerosis (MS).[17]

Nogo (= Reticulon 4, RTN4, Neurite Growth Inhibitor 220) one of several myelin-associated proteins with inhibitory effects for neuronal neurite outgrowth. Nogo exists as 3 splice transcript variants (NOGO-A, NOGO-B and NOGO-C) which are differentially expressed in the developing central nervous system. Also associated with autoimmune demyelination, shown in models of multiple sclerosis (MS) such as experimental autoimmune encephalomyelitis (EAE).

Nogo-A myelin-associated protein which can inhibit neurite outgrowth and prevent regeneration in the adult central nervous system. Secreted by oligodendrocytes in the central nervous system, but not by Schwann cells in the peripheral nervous system. (More? OMIM - Reticulon 4)

Glioma

References

  1. <pubmed>20506244</pubmed>
  2. <pubmed>20371817</pubmed>
  3. <pubmed>16832065</pubmed>PNAS
  4. <pubmed>17726524</pubmed>
  5. <pubmed>12761862</pubmed>
  6. <pubmed>12761864</pubmed>
  7. <pubmed>12761863</pubmed>
  8. <pubmed>20221422</pubmed>
  9. <pubmed>15285801</pubmed>
  10. <pubmed>17106878</pubmed>
  11. <pubmed>18490509</pubmed>| PMC2386097 | JCB
  12. <pubmed>17576794</pubmed>| PMC2064356 | JCB
  13. <pubmed>9485064</pubmed>
  14. <pubmed>15829523</pubmed>
  15. <pubmed>16034409</pubmed>
  16. <pubmed>17360586</pubmed>
  17. <pubmed>16632554</pubmed>

Journals

Online Textbooks

Developmental Biology (6th ed) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000. Formation of the Neural Tube | Differentiation of the Neural Tube | Tissue Architecture of the Central Nervous System | Neuronal Types | Snapshot Summary: Central Nervous System and Epidermis

Neuroscience Purves, Dale; Augustine, George J.; Fitzpatrick, David; Katz, Lawrence C.; LaMantia, Anthony-Samuel; McNamara, James O.; Williams, S. Mark. Sunderland (MA): Sinauer Associates, Inc. ; c2001 Early Brain Development | Construction of Neural Circuits | Modification of Brain Circuits as a Result of Experience

Molecular Biology of the Cell (4th Edn) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. New York: Garland Publishing; 2002. The three phases of neural development |

Search NLM Online Textbooks- "glial development" : Developmental Biology | Neuroscience | The Cell- A molecular Approach | Molecular Biology of the Cell | Endocrinology

Reviews

<pubmed>16314867</pubmed> <pubmed>19206138</pubmed>

Articles

<pubmed>18230116</pubmed> <pubmed>16388110</pubmed> <pubmed>12090403</pubmed> <pubmed>7522270</pubmed>

Search PubMed

Search Pubmed: Gliogenesis | Glial Development | Myelination

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Cite this page: Hill, M.A. (2024, March 28) Embryology Neural System - Glial Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_System_-_Glial_Development

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G