Sonic hedgehog expression in zebrafish forebrain identifies the teleostean pallidal signaling center and shows preglomerular complex and posterior tubercular dopamine cells to arise from shh cells

J Comp Neurol. 2020 Jun;528(8):1321-1348. doi: 10.1002/cne.24825. Epub 2019 Dec 10.


Ventralization, a major patterning process in the developing vertebrate neural tube (central nervous system, CNS), depends on Sonic hedgehog (SHH) as a main signaling morphogen. We studied the CNS of late larval and young adult zebrafish in a transgenic shh-GFP line revealing increased neuroanatomical detail due to the progressed differentiation state compared to earlier stages. Some major findings emerge from the present study. (a) shh -GFP is still expressed along the adult zebrafish CNS neuraxis in most locations seen in larvae. (b) We newly identify a ventroposterior shh pallidal domain representing the basal telencephalic signaling center important for basal ganglia development known in other vertebrates (i.e., the anterior entopeduncular area-basal medial ganglionic eminence of mammals). (c) We further show late-emerging shh-GFP positive radial glia cells in the medial zone of the dorsal telencephalon (i.e., the teleostan pallial amygdala). (d) Immunostains for tyrosine hydroxylase demonstrate that there is selective colocalization in adult dopamine cells with shh-GFP in the posterior tuberculum, including in projection cells to striatum, which represents a striking parallel to amniote mesodiencephalic dopamine cell origin from shh expressing floor plate cells. (e) There is no colocalization of shh and islet1 as shown by respective shh-GFP and islet1-GFP lines. (f) The only radially far migrated shh-GFP cells are located in the preglomerular area. (g) There are no adult cerebellar and tectal shh-GFP cells confirming their exclusive role during early development as previously reported by our laboratory.

Keywords: RRID: AB 2201528; RRID: AB 2340817; RRID: AB_10000240; RRID: AB_2340364; floor plate; islet1; longitudinal gene expression; mesodiencephalic dopamine cells; pallium; posterior tuberculum; preglomerular complex; striatum; telencephalon; tyrosine hydroxylase; ventralization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Dopaminergic Neurons / chemistry
  • Dopaminergic Neurons / metabolism*
  • Gene Expression
  • Globus Pallidus / chemistry
  • Globus Pallidus / metabolism*
  • Hedgehog Proteins / analysis
  • Hedgehog Proteins / biosynthesis*
  • Hedgehog Proteins / genetics
  • Prosencephalon / chemistry
  • Prosencephalon / metabolism*
  • Signal Transduction / physiology
  • Telencephalon / chemistry
  • Telencephalon / metabolism*
  • Zebrafish
  • Zebrafish Proteins / analysis
  • Zebrafish Proteins / biosynthesis*
  • Zebrafish Proteins / genetics


  • Hedgehog Proteins
  • Shha protein, zebrafish
  • Zebrafish Proteins