Journal of Neurocytology

, Volume 22, Issue 1, pp 1–13 | Cite as

An immunogold electron microscopic analysis of FMRFamide-like immunoreactive neurons in the CNS ofHelix pomatia: ultrastructure and synaptic connections

  • K. Elekes
  • J. Ude


The ultrastructure and synaptic connections of FMRFamide-like immunoreactive neurons were investigated in the CNS of the snailHelix pomatia, following the application of a post-embedding immunogold method. For comparison, first, we analyzed the ultrastructure and granule content of the identified FMRFamide-containing C3 neuron in the cerebral ganglion. Three types of unidentified immunoreactive neuronal perikarya, and five types of varicosities could be distinguished on the basis of granule content. The different granule types revealed a highly selective accumulation of gold particles. One granule type contained by one FMRFamide-like immunoreactive neuron type (N1) and by one varicosity type (T2) showed similar ultrastructure to that of the granules seen in the C3 cell. In the neuropil, the majority of FMRFamide-like immunoreactive varicosities (four of the five varicosity types) established specialized synaptic contacts with unidentified postsynaptic profiles. In the connective tissue sheath around the ganglia, three types of FMRFamide-like immunoreactive varicosities were found to establish unspecialized contacts with smooth muscle fibres or to be free in the mass of collagen fibres. On the basis of these observations, we suggest (1) an extensive diversity of the localization of FMRFamide (and related substances) at the ultrastructural level; (2) the involvement of FMRFamide-like immunoreactive varicosities in synaptic, modulatory and neurohormonal regulatory processes in theHelix nervous system.


Electron Microscopic Analysis Synaptic Connection Synaptic Contact Neuron Type Cerebral Ganglion 
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Copyright information

© Chapman and Hall Ltd 1993

Authors and Affiliations

  • K. Elekes
    • 1
  • J. Ude
    • 2
  1. 1.Balaton Limnological Research Institute of the Hungarian Academy of SciencesTihanyHungary
  2. 2.Department of Electron Microscopy, Institute of General Zoology and Animal PhysiologyFriedrich-Schiller-UniversityJenaFRG

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