Astroglial-mediated remodeling of the interhemispheric midline during telencephalic development is exclusive to eutherian mammalsReportar como inadecuado

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Neural Development

, 12:9

First Online: 30 May 2017Received: 26 February 2017Accepted: 12 May 2017DOI: 10.1186-s13064-017-0086-1

Cite this article as: Gobius, I., Suárez, R., Morcom, L. et al. Neural Dev 2017 12: 9. doi:10.1186-s13064-017-0086-1


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.

KeywordsInterhemispheric remodeling Interhemispheric fissure Corpus callosum Telencephalic commissure formation Abbreviations3VThird ventricle

EEmbryonic day

IHFInterhemispheric fissure

MZGMidline zipper glia

PPostnatal day

Autor: Ilan Gobius - Rodrigo Suárez - Laura Morcom - Annalisa Paolino - Timothy J. Edwards - Peter Kozulin - Linda J. Richards


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