Xenbase Image ID: 84072

Fig. 6. Schematic summary of transcription factor expression domains in the placodal ectoderm of neural plate stage Xenopus embryos. Transcription factors that control neuronal determination and differentiation and are expressed in all neurogenic placodes but excluded from adenohypophyseal and lens placodes are not included. The position of various prospective placodes within the panplacodal primordium (faint red) is indicated by colored rectangles. Colored lines enclose expression domains of the transcription factors listed at neural plate stages. Listing of transcription factors without asterisk refers to their expression domains established at neural plate stages, while listing of transcription factors preceded by asterisks refers to expression domains established at later stages. Question marks indicate tentative assignments because precise domain boundaries cannot be determined unambiguously from published information. For simplicity, some details of expression are ignored (for example, Msx1 and Msx 2 are strongly expressed only in the dorsal part of the indicated region). For details and references, see Fig. 5. Note that there are two foci of transcription factor expression, one centered on an anterior placodal area (with prospective adenohypophyseal and olfactory placodes), the other centered on a posterior placodal area (with prospective lateral line, otic, and epibranchial placodes). However, the spatial extension of various expression domains differs resulting in two nested hierarchies, which are overlapping in the regions of profundal and trigeminal placodes. For detailed explanation, see text. Abbreviations: Ad: adenohypophyseal placode; EB: epibranchial placodes; L: lens placode; LL: lateral line placodes; Ol: olfactory placode; Ot: otic placode; Pr: profundal placode; V: trigeminal placode. Image published in: Schlosser G (2006) Copyright © 2006. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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