Evolution of Cortical Lamination: the Reelin/Dab1 Pathway

  1. Gregory R. Bock and
  2. Gail Cardew
  1. Isabella Bar and
  2. André M. Goffinet

Published Online: 29 APR 2008

DOI: 10.1002/0470846631.ch9

Evolutionary Developmental Biology of the Cerebral Cortex: Novartis Foundation Symposium 228

Evolutionary Developmental Biology of the Cerebral Cortex: Novartis Foundation Symposium 228

How to Cite

Bar, I. and Goffinet, A. M. (2000) Evolution of Cortical Lamination: the Reelin/Dab1 Pathway, in Evolutionary Developmental Biology of the Cerebral Cortex: Novartis Foundation Symposium 228 (eds G. R. Bock and G. Cardew), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/0470846631.ch9

Author Information

  1. Neurobiology Unit, University of Namur Medical School, Namur, Belgium

Publication History

  1. Published Online: 29 APR 2008
  2. Published Print: 22 MAY 2000

Book Series:

  1. Novartis Foundation Symposia

Book Series Editors:

  1. Novartis Foundation

ISBN Information

Print ISBN: 9780471979784

Online ISBN: 9780470846636

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Keywords:

  • cerebral cortex;
  • lamination;
  • reelin;
  • Dab1;
  • evolution;
  • development;
  • radial orientation

Summary

The mammalian cortical plate is characterized by its radial organization and its inside–outside developmental gradient. Observations on reelin and Dab1-deficient mice show that reelin and Dab1 are both required to develop radial cortical organization and a normal maturation gradient. In the reptilian cortex, radial organization varies among species; it is the most rudimentary in turtles and the most elaborate in lizards, and can be described as intermediate in other species such as crocodilians and Sphenodon. On the other hand, the gradient of corticogenesis is directed from outside to inside in all reptiles studied, as well as in mice that are deficient in reelin, Dab1, as well as cyclin-dependent kinase 5 (Cdk5) and p35. All reptiles, even turtles, have reelin-expressing cells in the embryonic marginal zone. Mammals are characterized by a drastic increase in the number of reelin-positive cells (Cajal–Retzius cells) as well as by an amplification of reelin expression per cell. In lizards, the pattern of reelin expression is different, as reelin-expressing cells are also present below the cortical plate. In all mammalian and reptilian species, Dab1 is expressed in cortical plate cells. These data suggest that the reelin/Dab1 pathway was a driver of cortical evolution on the synapsid lineage and that similarities in radial cortical organization between squamates and mammals result from evolutionary convergence.