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Fig. 1. insm1 is expressed in retinal progenitor cells (RPCs). A. Schematic representation of the mature Xenopus tadpole retina. B – J. In situ hybridization performed using sectioned Xenopus laevis embryos. insm1 is expressed in retinal progenitor cells (RPCs) and undifferentiated neuroepithelium at stage 38. At stages 41 (C, H) and stage 45 (D), insm1 expression was detected in RPCs located in zones 2 and 3 of the ciliary marginal zone (CMZ) but not in the retinal stem cells of zone 1. Compare the expression of insm1 at stage 41 (C, H) to expression of notch1, a zone 2 marker, at stage 41 (F, I). Both are absent in the most distal zone 1 of the CMZ. Also compare the proximal expression of insm1 (C, H) to zone 3 and 4 marker, neuroD at stage 41 (G, J). The CMZ is indicated by black brackets. Scale bars (1 μM) for (B – G) and (H – J) are indicated in (A) and (F), respectively. Abbreviations: GL – ganglion cell layer, INL – inner nuclear layer, PL – photoreceptor layer. |