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Fig. 1. Ionocytes (cells expressing ion modulators) show a scattered epidermal distribution. (A) Images of whole-mounted X. tropicalis tadpole skin (stage 27) showing that ciliated cells, visualised with an α1-tubulin probe, and goblet cells, recognised by staining with an anti-lectin antibody, anti-xeel (red), account for the majority of cells in this tissue. However, a cell type that does not express either α1-tubulin nor xeel is also present (arrow). Approximately 60% of cells in this tissue are goblet cells, 18% are ciliated cells and approximately 22% represent an uncharacterised cell type(s). (B) Model for the development of the mucociliary epidermis of Xenopus. During the early neurula stage, ciliated cells (red) and other INCs (green) are specified in the inner epidermal layer (1; yellow). By the late neurula stage, both cell types intercalate into the outer layer (2; blue), where ciliated cells undergo ciliogenesis (3) [modified from Stubbs et al. (Stubbs et al., 2006)]. (C) Several ion transporters and enzymes show a scattered, punctate expression pattern in the epidermis by in situ hybridisation. This includes three subunits of the v-atpase enzyme complex (v1a, v1g and v0d), ca12 (also expressed in the otic vesicle and olfactory placode), slc26a4 (pendrin) and mct4 (also expressed in the somites). ov, otic vesicle; op, olfactory placode; s, somites. (D) Sectioning of embryos probed for v1a or ca12 (red) by fluorescent in situ hybridisation and DAPI staining for nuclei (blue). At the neurula stage (stage 14), cells expressing v1a and ca12 are located in the inner layer of the epidermis and then move into the outer layer by tailbud stage (stage 25). Scale bars: 50 μm (A,D); 250 μm (C). |
