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Selective early expression of the orphan nuclear receptor Nr4a2 identifies the claustrum homologue in the avian mesopallium: Impact on sauropsidian/mammalian pallium comparisons

Research output: Contribution to journalArticle

  • L Puelles
  • A Ayad
  • A Alonso
  • J E Sandoval
  • M Martínez-de-la-Torre
  • L Medina
  • J L Ferran

Related Edinburgh Organisations

Original languageEnglish
JournalJournal of Comparative Neurology
DOIs
Publication statusPublished - 24 Sep 2015

Abstract

The transcription factor Nr4a2 was recently revealed as a very early developmental marker of the claustrum proper in the mouse. The earliest claustral primordium was identified superficially, dorsally to the olfactory cortex, and was subsequently covered by the Nr4a2 -negative cells of the insular cortex (Puelles, 2014). Some tangentially migrating claustral derivatives (subplate cells, some endopiriform elements) also expressed this marker. In the present study, we employed the same genetic marker to explore the presence of a comparable pallial division in chicken, where in principle the same pallial sectors exist as in mammals. We were indeed able to delineate an early-developing Nr4a2-positive mantle domain at the expected topological position within the developing chicken lateral pallium (LPall). In the chicken, as well as in the turtle (from data in the literature), the earliest postmitotic lateropallial cells likewise express Nr4a2 and occupy a corticoid superficial stratum of the mesopallium, which is clearly comparable in spatial and chronological profile to the mouse claustrum. Other cells produced in this pallial sector include various tangentially migrating Nr4a2-labeled derivatives, as well as Nr4a2-negative and Nr4a2-positive local deeper subpopulations that partially interdigitate, forming mesopallial core and shell populations. We hold that the deep avian and reptilian mesopallial formation developing under the superficial corticoid claustrum homologue represents a field-homologue of the insula, though additional studies are needed to underpin this hypothesis. This article is protected by copyright. All rights reserved.

ID: 22210484