Internal extraocular photoreceptors in a dipteran insect

Synaptic connections between eyelet photoreceptors and pigment dispersing factor‐immunoreactive neurons of the blowfly Protophormia terraenovae

“…The first group, in the optic lobe, includes two types of extraretinal photoreceptors: the first one lies on the surface of the optic lobe and has well-developed rhabodmeres (Diptera: Seifert et al, 1987;Yasuyama and Meinertzhagen, 1999;Coleoptera: Schulz et al, 1984;Trichoptera, Hagberg, 1986), and the other has an elongated structure with less-developed rhabdomeric microvilli housed in the anterior margin of the lamina and lobula (Coleoptera: Fleissner et al, 1993;Blattaria: Fleissner et al, 2001). Among these extraretinal photoreceptors a pair of minute photoreceptor clusters underneath the retina at the posterior margin of the compound eye in Drosophila melanogaster (Hofbauer and Buchner, 1989), known as the "Hofbauer-Buchner" (H-B) eyelet, has been studied most intensively regarding its pattern of projection, developmental origin, ultrastructure, and function in circadian rhythmicity (Yasuyama and Meinertzhagen, 1999;Helfrich-Förster et al, 2002;Malpel et al, 2002;Rieger et al, 2003).…”

“…The Ocellus I derives from larval stemmata and might therefore be homologous to the H-B eyelet. P. cinerea also has a second, smaller pair of extraretinal photoreceptors (called Ocellus II) (Seifert et al, 1987). In the flies C. vicina and Musca domestica, four to five histamine-like immunoreactive fibers run from the region of the posterior lamina to the accessory medulla (Nä ssel et al, 1988), suggesting that these flies also have extraretinal photoreceptors corresponding to the H-B eyelet.…”

“…proaches, fall into three groups: the first group resides in the optic lobe (e.g., Diptera: Seifert et al, 1987;Hofbauer and Buchner, 1989; Coleoptera (beetle): Schulz et al, 1984;Fleissner et al, 1993;Felisberti et al, 1997;Blattaria: Fleissner et al, 2001;Lepidoptera, Ichikawa, 1991;Hymenoptera: Felisberti and Ventura, 1996;Trichoptera: Hagberg, 1986); and the second is located in the central brain (Coleoptera (firefly) : Hariyama, 2000; Orthoptera: Lundquist et al, 1996; Aphididae: Gao et al, 1999;Diptera: Cymborowski and Korf, 1995;Lepidoptera: Kono et al, 1983;Shimizu et al, 2001; Decapoda: Sandeman et al, 1990). These two groups are often postulated to function in the entrainment of circadian rhythms and in the photoperiodic responses (for a review, see Numata et al, 1997).…”

Nonvisual Photoreceptors in Arthropods with Emphasis on Their Putative Role as Receptors of Natural Zeitgeber Stimuli

“…In adult insects, they never keep their dioptric apparatus or ommatidial structure, which would be essential for image recognition. Sometimes without relating these organs to larval eyes, stemmata, or their derivatives, the metamorphosized and internalized stemmata have been described in several insect orders as ''brain photoreceptors'' or ''extraocular photoreceptors'' (e.g., in ants: Felisberti and Ventura, 1996;in beetles: Mischke and Wellmann, 1985;Schultz et al, 1984;in butterflies: Mischke and Ziegler, 1987;Ichikawa, 1991;in caddiesflies: Hagberg, 1986; in flies: Seifert et al, 1987). Also, the Bolwig organ of Dipteran insects is a modified larval eye (Melzer and Paulus, 1989) and can be found in Drosophila as an ''eyelet'' in the compound eye's posterior margin (Hofbauer and Buchner, 1989;Yasuyama and Meinertzhagen, 1999).…”

Expression of UV-, blue-, long-wavelength-sensitive opsins and melatonin in extraretinal photoreceptors of the optic lobes of hawkmoths

“…The photoreceptor basis of circadian and photoperiodic rhythms is less well understood for lepidopterans but, in addition to the compound eyes, extraretinal photoreceptors homologous to the Drosophila extraretinal Hofbauer-Buchner eyelet (Melzer and Paulus 1989) have been characterized anatomically and physiologically (Ichikawa 1991). In other insect orders, these adult stemmata have been found in hymenopterans (Felisberti and Ventura 1996), dipterans other than Drosophila (Seifert et al 1987), coleopterans (Schulz et al 1984;Felisberti et al 1997;Hariyama 2000;Fleissner and Fleissner 2003) and trichopterans (Hagberg 1986), suggesting a similar role for this photoreceptive organ in the entrainment of circadian rhythms in insects.…”