Neural control of heartbeat in onychophoran species

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The central nervous system of Onychophora consists of the large bilobed cerebral ganglion, a pair of circumoesophageal connectives, the stomodeal connective and widely separated paired ventral nerve cords. We have localized FMRFamide- and serotonin-like immunoreactivity in an onychophoran Euperipatoides kanangrensis by means of light microscopic immunocytochemical techniques.1. FMRFamide-like immunoreactive neuronal cell bodies were observed in the central nervous system. The immunoreactive cell bodies were located diffused in the oesophagus and the gut. There were a pair of regions with clustered FMRFamide-like immunoreactive glomeruli at basal parts of the antennal nerves in the cerebral ganglion. The retina, optic ganglia and optic tracts showed immunoreactivity. Immurioreactive neural processes were observed in the nerves to the heart, the alimentary duct, the oviduct, the oncopodia and the body muscles.2. Serotonin-like immunoreactivity was observed in cell bodies and neuronal pro … More cesses throughout the central nervous structures. The anntenal glomeruli located at basal parts of the antennal nerves in the cerebral ganglion showed Serotonin-like immunoreactivity, as well as FMRFamide-like immunoreactivity. The optic tract showed immunoreactivity, but the retina and optic ganglia did not. The foregut, midgut and hindgut contain immunoreactive cells in their walls. Immunoreactivity was also observed in a variety of peripheral nerves. Those are the unpaired dorsal nerve, paired nerves to the heart, salivary gland, foregut, midgut, hindgut, oviduct and circular, transverse and longitudinal body muscles. The dorsal nerve showed much intenser serotonin-like immunoreactivity than FMRFamide-like immunoreactivity. Serotonin-like immunoreactive neural processes were observed in the nephridium and sacculus located in the oncopodium.The results indicates that Onychophora is one of the phylogenetic taxa in which the presence of FMRFamide-like peptides have been proved. Serotonin may be used as a neurotransmitter for both motor and sensory nerves. Less