Combination of physiological and anatomical methods for studying extraocular photoreceptors on the genitalia of the butterfly, Papilio xuthus.

This paper describes a combination of electrophysiological and anatomical techniques useful for characterizing sensory neurons in insects in our studies on the extraocular photoreceptors on the genitalia of the butterfly, Papilio xuthus. Genital photoreceptors were first electrophysiologically identified by recording photoreceptor spikes in response to light stimulation of the genitalia. The precise location and ultrastructure of these photoreceptors were then studied by light and electron microscopy. Both electrophysiological and anatomical techniques employed here were rather classical, but, as shown in this paper, they appear to be particularly useful for systems where intracellular penetration is difficult.