DISTRIBUTION OF FMRFAMIDE-LIKE IMMUNOREACTIVITY IN THE NERVOUS-SYSTEMOF LUMBRICUS-TERRESTRIS

The distribution of FMRFamide-like immuno reactive cell bodies and fib ers in the nervous system of the earthworm Lumbricus terrestris is has been studied by means of immunocytochemistry. The cerebral ganglion c ontains 150-170 immunoreactive nerve cells that are organized into six major groups in the rostral and five major groups in the caudal part of the ganglion; 160-180 immunoreactive nerve cells are present in the subesophageal ganglion, and 80-90 in the ventral cord ganglia. Immuno reactive neurons of the subesophageal and the ventral cord ganglia sho w similar distributions, in that FMRFamide-like immunoreactive cells f orm a ventromedial and a lateral cell group. Neuropil in all parts of the central nervous system shows intensively stained varicose and non- varicose fibers. Each segmental nerve contains FMRFamide-like immunore active fibers that can partly be traced to the two muscle layers of th e body wall, and a fine immunoreactive network lies among the muscle f ibers. A similar network is found in the wall of the alimentary canal. Immunopositive perikarya and fibers have been detected in the prostom ial nerves, in the stomatogastric system. Some epithelial cells of the body wall are also immunopositive. The morphological characteristics and localization of FMRFamide immunoreactive neurons suggest that they may be involved in: (1) central integratory processes; (2) neuromuscu lar regulation in both the body wall and enteric system; (3) sensory p rocesses.