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Fig. 2. The intestinal epithelium thickens during metamorphic climax. Cross sections of the duodenum at different developmental stages are labeled with antibodies against proteins that are localized in the epithelium (e-cadherin, green) and mesenchyme (fibronectin, red). Nuclei are labeled with DAPI (white). (A and A′) Before metamorphosis (NF 54), the epithelium is only one to two cell layers thick. During metamorphic climax (B and B′,NF62; C and C′, NF 63), the epithelial layer becomes five to eight cell layers thick. (D and D′)At the end of climax (NF 66), the epithelium returns to one to two cell layers thick. [Scale bars: 100 μm (A–D) and 20 μm (A′–D′).] The boxed regions in A–D correspond with the magnified regions shown in A′–D′. |