MICROSCOPIC INVESTIGATION OF THE INNERVATION OF DORSO-VENTRAL MUSCLES IN THE PTEROPOD MOLLUSC, CLIONE LIMACINA

Sheila Ann Kitchen

The order Gymnostomata is comprised of the naked pteropods that have many morphological adaptations for a pelagic lifestyle. One of the species, Clione limacina, has been a model specimen for neurophysiological study of locomotion due to its basic neuronal control system. Clione swim through dorsal and ventral flapping movements of their wing-like parapodia. The central pattern generator (CPG) located in the pedal ganglia is the control center of locomotion and directs motor neurons located in the musculature of the parapodia (wings). Hyperpolarization-activated cation channel (HCN) markers were used locate the dorso-ventral muscle cells. Light microscopy showed labeling of the dorso-ventral muscles in the hemocoel, in between oblique swim muscles, and attached to the epithelium. Contractions of the muscles, at the various locations, decreases wing thickness creating a hydrostatic pressure that increases rigidity of the wings.