@article{oai:ir.soken.ac.jp:00004175,
 author = {蟻川, 謙太郎 and MIYAKO, Yumiko and ARIKAWA, Kentaro and EGUCHI, Eisuke},
 issue = {3},
 journal = {Journal of Comparative Neurology, Journal of Comparative Neurology},
 month = {Jan},
 note = {This paper describes the ultrastructure of a sensory neuron found in the extraocular photoreceptive site on the butterfly genitalia. Our previous studies have shown that there are two pairs of the photoreceptive sites in a butterfly (four per individual). Each photoreceptive site is recognizable by a transparent area in the pigmented cuticle of the genitalia. From the nerve that extends from the transparent cuticle to the last abdominal ganglion, a sustained train of single unit spikes can be recorded in response to a light flash. The single unit spikes disappear when the transparent cuticle is covered, thus indicating that a single photoreceptor exists close to it.

Here, we examined complete serial semithin sections of plastic-embedded photoreceptive sites of both male and female, and observed an ovoid structure close to the transparent cuticle. The structure contained the cell body of a sensory neuron whose axon was in the nerve branch from which the photoresponse had been recorded. Further electron microscopy revealed that the cell body extended a few distal processes that protrude tubular membrane from the tip, forming a structure resembling the phaosome (from Greek;phaos = light, some = body) which was first described in the earthworm dermal photoreceptors. The sensory neuron was also found in a surgically isolated nerve-photoreceptor preparation that responded to the light. We therefore propose that the phaosome-containing sensory neuron is the butterfly genital photoreceptor.},
 pages = {458--468},
 title = {Ultrastructure of the extraocular photoreceptor in the genitalia of a butterfly, Papilio xuthus},
 volume = {327},
 year = {1993}
}