{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T15:26:06Z","timestamp":1781105166270,"version":"3.54.1"},"reference-count":55,"publisher":"National Academy of Sciences","issue":"26","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2008,7]]},"abstract":"<jats:p>\n                    Ectopic expression of the retinal determination gene\n                    <jats:italic>eyeless<\/jats:italic>\n                    (\n                    <jats:italic>ey<\/jats:italic>\n                    ) induces the formation of supernumerary eyes on antennae, legs, wings, and halteres. These ectopic eyes form ommatidia that contain photoreceptors and accessory cells and respond to light. Here, we demonstrate that ectopic eyes on antennae and legs extend axonal projections to the central nervous system. Furthermore, electroretinograms and morphological evidence indicate that the photoreceptor axons of at least the antennal ectopic eyes can form completely constituted ectopic synapses with foreign postsynaptic elements and suggest that transmission at these sites may be functional. However, the ectopic axons do not connect to their correct optic lobe targets and do not project deeply into the neuropile, but rather form synapses at superficial positions in the neuropils. By means of confocal and electron microscopy we show that these ectopic synapses resemble normal synapses, albeit with some distinct morphological differences. Our data strongly suggest that the developmental programs controlling photoreceptor synaptogenesis and visual map formation depend to a considerable extent on presynaptic and thus photoreceptor-autonomous steps. Our data also suggest that photoreceptor axon projections and the establishment of the highly stereotypical neural circuitry in the optic lobe, the normal target neuropil, may depend on target-specific cues that appear to be absent from the antennal lobe and thoracic ganglion.\n                  <\/jats:p>","DOI":"10.1073\/pnas.0803254105","type":"journal-article","created":{"date-parts":[[2008,6,24]],"date-time":"2008-06-24T22:38:38Z","timestamp":1214347118000},"page":"8968-8973","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":20,"title":["Central projections of photoreceptor axons originating from ectopic eyes in\n                    <i>Drosophila<\/i>"],"prefix":"10.1073","volume":"105","author":[{"given":"Jason","family":"Clements","sequence":"first","affiliation":[{"name":"*Laboratory of Developmental Genetics, Vlaams Instituut voor Biotechnologie (VIB) and"},{"name":"Center for Human Genetics, Katholieke Universiteit Leuven, Herestraat 49 bus 602, B-3000 Leuven, Belgium;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiyuan","family":"Lu","sequence":"additional","affiliation":[{"name":"Neuroscience Institute and Department of Psychology, Dalhousie University, Life Sciences Center, Halifax, NS, Canada B3H 4J1; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Walter J.","family":"Gehring","sequence":"additional","affiliation":[{"name":"Department of Cell and Developmental Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ian A.","family":"Meinertzhagen","sequence":"additional","affiliation":[{"name":"Neuroscience Institute and Department of Psychology, Dalhousie University, Life Sciences Center, Halifax, NS, Canada B3H 4J1; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrick","family":"Callaerts","sequence":"additional","affiliation":[{"name":"*Laboratory of Developmental Genetics, Vlaams Instituut voor Biotechnologie (VIB) and"},{"name":"Center for Human Genetics, Katholieke Universiteit Leuven, Herestraat 49 bus 602, B-3000 Leuven, Belgium;"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2008,7]]},"reference":[{"key":"e_1_3_3_1_2","first-page":"1363","volume-title":"The Development of Drosophila melanogaster","author":"Meinertzhagen I","year":"1993","unstructured":"I Meinertzhagen, TE Hanson, The development of the optic lobe. 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