| Summary: | 碩士 === 國立臺灣大學 === 生命科學系 === 103 === Since the melanopsin was discovered, the novel photoreceptor, melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs), have been shown to participate in many non-image forming functions such as circadian rhythms and pupillary light reflex. While most ipRGCs express brn3b (POU4F2), the general transcription factor for retinal ganglion cells development, a portion of ipRGCs do not express brn3b and dominantly innervate suprachiasmatic nucleus (SCN), which is the central clock for circadian rhythm in mammals. In retinal development, different time points of cell differentiation strongly imply different cell types. To identify differentiation time point of brn3b negative ipRGCs, we used 5-ethynyl-2’-deoxyuridine (EdU) and melanopsin immunostaining to label mitotic ipRGCs at specific embryonic stage in wild type mice and transgenic mice without brn3b-expressing ipRGCs. Our data show that brn3b negative ipRGCs and the whole population of ipRGCs derive from retinal progenitor cells in the same period. Further analysis in spatial
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distribution discovered slight difference at progression of development. In addition, to assess the circadian rhythms that brn3b negative M1 ipRGCs and SCN involve, circadian phase shift experiments of one-eye light pulse and two-eye light pulse were done, and the results provide some insights for researches in the future.
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