Astroglial-mediated remodeling of the interhemispheric midline during telencephalic development is exclusive to eutherian mammals

Gobius, Ilan, Suarez, Rodrigo, Morcom, Laura, Paolino, Annalisa, Edwards, Timothy J., Kozulin, Peter and Richards, Linda J. (2017) Astroglial-mediated remodeling of the interhemispheric midline during telencephalic development is exclusive to eutherian mammals. Neural Development, 12 1: 9-9. doi:10.1186/s13064-017-0086-1


Author Gobius, Ilan
Suarez, Rodrigo
Morcom, Laura
Paolino, Annalisa
Edwards, Timothy J.
Kozulin, Peter
Richards, Linda J.
Title Astroglial-mediated remodeling of the interhemispheric midline during telencephalic development is exclusive to eutherian mammals
Journal name Neural Development   Check publisher's open access policy
ISSN 1749-8104
Publication date 2017-05-30
Year available 2017
Sub-type Article (original research)
DOI 10.1186/s13064-017-0086-1
Open Access Status DOI
Volume 12
Issue 1
Start page 9
End page 9
Total pages 7
Place of publication London, United Kingdom
Publisher BioMed Central
Language eng
Abstract The corpus callosum forms the major interhemispheric connection in the human brain and is unique to eutherian (or placental) mammals. The developmental events associated with the evolutionary emergence of this structure, however, remain poorly understood. A key step in callosal formation is the prior remodeling of the interhemispheric fissure by embryonic astroglial cells, which then subsequently act as a permissive substrate for callosal axons, enabling them to cross the interhemispheric midline. However, whether astroglial-mediated interhemispheric remodeling is unique to eutherian mammals, and thus possibly associated with the phylogenetic origin of the corpus callosum, or instead is a general feature of mammalian brain development, is not yet known. To investigate this, we performed a comparative analysis of interhemispheric remodeling in eutherian and non-eutherian mammals, whose lineages branched off before the evolution of the corpus callosum. Whole brain MRI analyses revealed that the interhemispheric fissure is retained into adulthood in marsupials and monotremes, in contrast to eutherians (mice), in which the fissure is significantly remodeled throughout development. Histological analyses further demonstrated that, while midline astroglia are present in developing marsupials, these cells do not intercalate with one another through the intervening interhemispheric fissure, as they do in developing mice. Thus, developing marsupials do not undergo astroglial-mediated interhemispheric remodeling. As remodeling of the interhemispheric fissure is essential for the subsequent formation of the corpus callosum in eutherians, our data highlight the role of astroglial-mediated interhemispheric remodeling in the evolutionary origin of the corpus callosum.
Keyword Interhemispheric remodeling
Interhemispheric fissure
Corpus callosum
Telencephalic commissure formation
Q-Index Code C1
Grant ID 1048849
DP160103958
Institutional Status UQ

 
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