Author/Editor		Verkhratsky, Alexei; Ho, Margaret S.; Parpura, Vladimir
Title		Evolution of neuroglia
Type		članek
Source		In: Neuroglia in neurodegenerative diseases Singapore : Springer
Publication year		2019
Volume		str. 15-44
ISSN		2214-8019 - Advances in experimental medicine and biology
Language		eng
Abstract		As the nervous system evolved from the diffused to centralised form, the neurones were joined by the appearance of the supportive cells, the neuroglia. Arguably, these non-neuronal cells evolve into amore diversified cell family than the neurones are. The first ancestral neuroglia appeared in flatworms being mesenchymal in origin. In the nematode C. elegans proto-astrocytes/supportive glia of ectodermal origin emerged, albeit the ensheathment of axons by glial cells occurred later in prawns. The multilayered myelin occurred by convergent evolution of oligodendrocytes and Schwann cells in vertebrates above the jawless fishes.Nutritive partitioning of the brain from the rest of the body appeared in insects when the hemolymph-brain barrier, a predecessor of the blood-brain barrier was formed. The defensive cellular mechanism required specialisation of bona fide immune cells, microglia, a process that occurred in the nervous system of leeches, bivalves, snails, insects and above. In ascending phylogeny, newtype of glial cells, such as scaffolding radial glia, appeared and as the bran sizes enlarged, the glia to neurone ratio increased. Humans possess some unique glial cells not seen in other animals.
Keywords		astrociti velikost možganov razmerje med glijo in nevronom astrocytes brain size glia to neuron ratio