title: Ultrastructure of the bimodal pacemaker neuron in the central nervous system of Helix pomatia L.
abstract: Fine structure of the identified (RPal) giant neuron of Helix pomatia has been investigated after isolation. The following findings have been established: 1. The cytoplasm of the RPal neuron is electron-microscopically characterized by a strongly invaginated nuclear envelope, a highly-developed rER system, a large number of free ribosomes and by 110-250 nm-sized neurosecretory-like granules with finely-granulated inner content. 2. The fine-structural arrangement of the cytoplasm exhibited a seasonal variation, viz. in winter it was found to be layered, while in spring it showed a homogeneous structure. 3. On the cell surface free axon profiles containing vesicles were sometimes found, which might be afferent connections to the cell body.
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D006372:Helix, Snails / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009474:Neurons / Q000648:ultrastructure*; D012270:Ribosomes / Q000648:ultrastructure; D012621:Seasons