IMMUNOLABELED NEUROACTIVE SUBSTANCES IN THE OSPHRADIUM OF THE POND SNAIL LYMNAEA-STAGNALIS

The osphradium of molluscs is assumed to be a sensory organ. The prese nt investigation in Lymnaea stagnalis has established two ultrastructu rally different types of dendrites in the sensory epithelium. Cells im munoreactive to leucine-enkephalin and FMRFamide send processes to the sensory epithelium. These neurons of the osphradial ganglion are thus considered to be part of the sensory system, as are methionine-enkeph alin-immunoreactive cells in the mantle wall in the vicinity of the os phradium. The complexity of the osphradial ganglion is further demonst rated by serotonin-immunoreactive neurons innervating the muscular coa t around the osphradial canal and methionine-enkephalin-immunoreactive cells sending projections to the central nervous system.