The terminal nerve in turbot, Psetta maxima: a developmental immunocytochemical study

Area of Science:

• Neuroscience
• Developmental Biology
• Ichthyology

Background:

• The terminal nerve (TN) is a poorly understood cranial nerve system in vertebrates.
• Its ontogeny and neurochemical composition in teleosts, particularly during early development, remain largely uncharacterized.

Purpose of the Study:

• To investigate the developmental pattern and organization of the terminal nerve (TN) in turbot.
• To identify the neurochemical nature of immunoreactive material within the developing TN.

Main Methods:

• Utilized an antiserum against neuropeptide Y to trace the development of the TN in larval turbot.
• Performed preabsorption experiments with neuropeptide Y and FMRF-amide to identify the immunoreactive substances.

Main Results:

• Immunoreactive cells of the TN were first detected in the olfactory placode at hatching and formed an extracranial ganglion.
• Labeled neurons migrated along the olfactory nerve to the forebrain and olfactory bulb, with projections to the brain and retina.
• The generation of TN cells continued into metamorphosis, with distorted localization due to turbot's asymmetric development.
• Preabsorption tests indicated the immunoreactive material was not neuropeptide Y, but potentially FMRF-amide-like peptides.

Conclusions:

• The study elucidates the ontogeny and migration patterns of the terminal nerve in turbot during early development.
• Findings suggest the presence of FMRF-amide-like peptides, rather than neuropeptide Y, in the turbot terminal nerve, highlighting potential diversity in teleost neurochemistry.