The nervus terminalis in amphibians: anatomy, chemistry and relationship with the hypothalamic gonadotropin-releasing hormone system

Brain Behav Evol. 1988;32(3):141-50. doi: 10.1159/000116541.


The nervus terminalis (TN), a component of the olfactory system, is found in most vertebrates. The TN of some fishes and mammals contains neurons immunoreactive (ir) to gonadotropin-releasing hormone (LHRH), and to several other neuropeptides and neurotransmitter systems, but there is little information on TN chemistry in other vertebrate taxa. Using immunocytochemical techniques, we found LHRH-ir neurons in amphibian TNs. In anurans, but not in a urodele, the TN was also found to contain Phe-Met-Arg-Phe-NH2 (FMRFamide) immunoreactivity. LHRH-ir neurons of the TN and those of the septal-hypothalamic system are morphologically homogeneous and form a distinct anatomical continuum in amphibians. Based upon topographical and cytological criteria, we hypothesize that LHRH-ir systems in vertebrates might derive embryonically from the TN.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Cranial Nerves / anatomy & histology*
  • FMRFamide
  • Gonadotropin-Releasing Hormone / metabolism*
  • Hypothalamus / anatomy & histology*
  • Immunoenzyme Techniques
  • Nerve Fibers / anatomy & histology
  • Neurons / ultrastructure
  • Neuropeptides / metabolism
  • Olfactory Nerve / anatomy & histology*
  • Olfactory Pathways / anatomy & histology
  • Rana pipiens / anatomy & histology*
  • Ranidae / anatomy & histology*
  • Salamandridae / anatomy & histology*


  • Neuropeptides
  • Gonadotropin-Releasing Hormone
  • FMRFamide