Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

According to Fernando García-Moreno and Zoltán Molnár understanding development and evolution of the neocortex has important implications. Differential timing of developmental events sculpts the brains of different species into distinct organs. The latest investigations on the development of the dorsal forebrain in chick and mouse embryos showed a major difference between vertebrate brains. A delay in the neurogenic properties of a subset of progenitors is specific to mammals and could be responsible for the evolutionary origin of the corpus callosum...

PNAS Publication 1

Fernando García-Moreno and Zoltán Molnár publish a paper in PNAS, Subset of early radial glial progenitors that contribute to the development of callosal neurons is absent from avian brain, showing an interesting divergence of the embryonic development of the forebrain of vertebrate species.

The classical view of mammalian cortical development suggests that pyramidal neurons are generated in a temporal sequence, with all radial glial cells (RGCs) contributing to both lower and upper neocortical layers. A recent opposing proposal suggests there is a subgroup of fate-restricted RGCs in the early neocortex, which generates only upper-layer neurons. Little is known about the existence of fate restriction of homologous progenitors in other vertebrate species. We investigated the lineage of selected Emx2+ [vertebrate homeobox gene related to Drosophila empty spiracles (ems)] RGCs in mouse neocortex and chick forebrain and found evidence for both sequential and fate-restricted programs only in mouse, indicating that these complementary populations coexist in the developing mammalian but not avian brain. Among a large population of sequentially programmed RGCs in the mouse brain, a subset of self-renewing progenitors lack neurogenic potential during the earliest phase of corticogenesis. After a considerable delay, these progenitors generate callosal upper-layer neurons and glia. On the other hand, we found no homologous delayed population in any sectors of the chick forebrain. This finding suggests that neurogenic delay of selected RGCs may be unique to mammals and possibly associated with the evolution of the corpus callosum.

 

FIGURE: Mammalian but not avian forebrain stem/progenitor cells labelled through Emx2 promoter sequence show delayed neurogenesis.
Top row - Examples of the distribution of the cortical neurons in mouse E14, 2 days after electroporation with general and Emx2 promoter construct at E12.
Bottom row - Chick cases at E6, 2 days after electroporation at E4.
Left column - Labelled with EGFP, early progenitors of the forebrain generated neurons that migrated to the postmitotic areas (CP: cortical plate; MZ: mantle zone).
Right column - Also labelled with EGFP, early progenitors selected by their expression of Emx2 did not generate neurons in mouse (observe the absence of green cells in CP) but were neurogenic in chick (green cells were present in MZ).

 

More info on the PNAS website.

Stem cells with delayed neurogenesis and the evolution of callosal interhemispheric connections in the mammalian brain, Article on the Human Frontier Science Program website.

Similar stories

Key cause of type 2 diabetes uncovered

Research led by Dr Elizabeth Haythorne and Professor Frances Ashcroft reveals high blood glucose reprograms the metabolism of pancreatic beta-cells in diabetes. They have discovered that glucose metabolites, rather than glucose itself, are key to the progression of type 2 diabetes. Glucose metabolites damage pancreatic beta-cell function, so they are unable to release enough of the hormone insulin. Reducing the rate at which glucose is metabolised, and these glucose metabolites build up, can prevent the effects of hyperglycaemia.

New study shows clinical symptoms for Alzheimer’s can be predicted in preclinical models

Establishing preclinical models of Alzheimer’s that reflect in-life clinical symptoms of each individual is a critically important goal, yet so far it has not been fully realised. A new collaborative study from the University of Oxford has demonstrated that clinical vulnerability to an abnormally abundant protein in Alzheimer’s brain is in fact reflected in individual patient induced pluripotent stem cell-derived cortical neurons.

Updating the circuit maps of the sympathetic neural network

A new review from Professor Ana Domingos’ lab and colleagues offers a fresh modern viewpoint on sympathetic neurons and their relation to immune cells and obesity.

New Pfizer grant paves the way to a better understanding of how body fat is controlled

Professor Ana Domingos has been awarded a highly competitive independent research grant from Pfizer to discover ‘the role of Sympathetic-associated Perineurial barrier Cells in obesity’.

Collaborative MRC grant paves the way to new therapeutic targets for stress and anxiety disorders

Dr Armin Lak, Associate Professor Ed Mann and Professor Zoltán Molnár have been awarded a £733K Project Grant from the Medical Research Council on “Orexinergic projections to neocortex: potential role in arousal, stress and anxiety-related disorders”.