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. 2004 Apr 6;101(16):6231–6236. doi: 10.1073/pnas.0401149101

Fig. 3.

Fig. 3.

Daily profiles in the number of PER1-, PER2-, and CRY1-immunoreactive (-ir) cells in the SCN of 19-day fetuses. Pregnant rats maintained in LD12:12 were released into darkness at the time of the expected dark–light transition (CT0), and the fetal SCN were assayed for immunoreactivity during the first cycle in darkness. Data are means from four fetuses. Representative photomicrographs of coronal sections of SCN of 19-day fetuses assayed at CT6 (A, D, and G) and CT16 (B, E, and H) and of adult rats assayed at the expected time of the immunoreactivity maximum (C, F, and I) show PER1 (A–C), PER2 (D–F), and CRY1 (G–I) immunopositive cells.