Identification of the optic recess region as a morphogenetic entity in the zebrafish forebrain

Sci Rep. 2015 Mar 4:5:8738. doi: 10.1038/srep08738.


Regionalization is a critical, highly conserved step in the development of the vertebrate brain. Discrepancies exist in how regionalization of the anterior vertebrate forebrain is conceived since the "preoptic area" is proposed to be a part of the telencephalon in tetrapods but not in teleost fish. To gain insight into this complex morphogenesis, formation of the anterior forebrain was analyzed in 3D over time in zebrafish embryos, combining visualization of proliferation and differentiation markers, with that of developmental genes. We found that the region containing the preoptic area behaves as a coherent morphogenetic entity, organized around the optic recess and located between telencephalon and hypothalamus. This optic recess region (ORR) makes clear borders with its neighbor areas and expresses a specific set of genes (dlx2a, sim1a and otpb). We thus propose that the anterior forebrain (secondary prosencephalon) in teleosts contains three morphogenetic entities (telencephalon, ORR and hypothalamus), instead of two (telencephalon and hypothalamus). The ORR in teleosts could correspond to "telencephalic stalk area" and "alar hypothalamus" in tetrapods, resolving current inconsistencies in the comparison of basal forebrain among vertebrates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • ELAV-Like Protein 3 / genetics
  • ELAV-Like Protein 3 / metabolism
  • Embryo, Nonmammalian / anatomy & histology
  • Embryo, Nonmammalian / embryology
  • Embryo, Nonmammalian / metabolism
  • Gene Expression Regulation, Developmental
  • In Situ Hybridization, Fluorescence
  • Microscopy, Confocal
  • Models, Anatomic
  • Models, Genetic
  • Neurogenesis / genetics*
  • Preoptic Area / embryology
  • Preoptic Area / metabolism*
  • Prosencephalon / embryology
  • Prosencephalon / metabolism*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Time Factors
  • Zebrafish / embryology
  • Zebrafish / genetics*
  • Zebrafish / metabolism
  • Zebrafish Proteins / genetics
  • Zebrafish Proteins / metabolism


  • Basic Helix-Loop-Helix Transcription Factors
  • ELAV-Like Protein 3
  • Repressor Proteins
  • Sim1a protein, zebrafish
  • Zebrafish Proteins
  • elavl3 protein, zebrafish