{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T16:26:37Z","timestamp":1781108797781,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"2","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1973,2]]},"abstract":"<jats:p>\n                    The central connections of retinal ganglion cells are retinotopically organized, producing a \u201cmap\u201d of the retina on the surface of the optic tectum. Exactly how and when individual ganglion cells develop the position-dependent properties (termed\n                    <jats:italic>locus specificities<\/jats:italic>\n                    ) subserving formation of the map is unknown, but the positional information that each ganglion cell will use in this process is specified in the early\n                    <jats:italic>Xenopus<\/jats:italic>\n                    embryo during a critical period at stages 28-32. We report two methods for isolating eye primordia from the axial cues of the animals during this critical period and for then allowing the eyes to form retinotectal connections in a carrier embryo. The results show that, as early as optic vesicle stages 22-23, the eyes already contain orthogonal reference axes, that positional information can be specified with respect to these axes\n                    <jats:italic>in vitro<\/jats:italic>\n                    , and that the\n                    <jats:italic>specification<\/jats:italic>\n                    process itself may only entail a transition from a reversible to an irreversible state.\n                  <\/jats:p>","DOI":"10.1073\/pnas.70.2.507","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T02:42:38Z","timestamp":1149043358000},"page":"507-511","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":37,"title":["Specification of Positional Information in Retinal Ganglion Cells of\n                    <i>Xenopus:<\/i>\n                    Assays for Analysis of the Unspecified State"],"prefix":"10.1073","volume":"70","author":[{"given":"R. K.","family":"Hunt","sequence":"first","affiliation":[{"name":"Department of Anatomy, University of Pennsylvania Medical School, Philadelphia, Pa. 19104"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcus","family":"Jacobson","sequence":"additional","affiliation":[{"name":"The Thomas C. Jenkins Department of Biophysics, The Johns Hopkins University, Baltimore, Maryland 21218"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1973,2]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.70.2.507","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T10:39:23Z","timestamp":1649846363000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.70.2.507"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1973,2]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1973,2]]}},"alternative-id":["10.1073\/pnas.70.2.507"],"URL":"https:\/\/doi.org\/10.1073\/pnas.70.2.507","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1973,2]]},"assertion":[{"value":"1973-02-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}