INNERVATION OF COPEPOD ANTENNULES INVESTIGATED USING LASER-SCANNING CONFOCAL MICROSCOPY

The antennules of calanoid copepods compose one of the primary organs for remote sensing of mechanical and chemical environmental stimuli. T o better understand how these sensory structures interface with the 3- dimensional fluid environment, it is necessary to understand both thei r functional morphology and their physiology. These appendages possess setae which are the suspected sites of signal transduction. Ultrastru ctural studies reveal that the setae differ in their patterns of inner vation. and it is believed that these dissimilarities reflect differen ces in function. In this study, we label the sensilla of copepod anten nules using a fluorescent carbocyanine dye, DiI, which becomes inserte d in the lipid bilayer of neuronal cell membranes. Aesthetascs on the antennules can then be identified using standard fluorescent microscop y. Because the copepod exoskeleton is transparent to the laser, we wer e able to utilize laser scanning confocal microscopy to identify other neuronal structures and patterns of musculature within the antennule, while simultaneously visualizing the orientation and larger scale str ucture of the sensilla.